Radiation has diverse applications including tracing chemical reactions using radioactive isotopes, measuring material thickness with alpha/beta particles, radioactive dating (carbon-14 with 5,730-year half-life), cancer treatment, food preservation, and nuclear power generation through controlled fission. However, radiation poses significant health risks including leukemia (main cancer type), genetic mutations, and tissue damage, with alpha particles being 20 times more harmful than beta/gamma for the same absorbed dose. Nuclear power plants use controlled fission chains with uranium/plutonium fuel, control rods, and coolant systems to generate electricity while avoiding greenhouse gas emissions, though they face challenges with expensive safety measures, long-lived radioactive waste, and public concerns from historical accidents like Chernobyl.
Physics Wk5 Ca 7.6-7.7 (by zaina)Added:
Hi, I'm Z. I'm going to be doing the physics CA for 7.6 and 7.7.
For a start, I'm just going to explain a few things.
Okay. Basically, um there's a lot of uses for radiation. So, we can use it like um to achieve certain things like in commercially and like in industries.
So there's six different uses for radiation. The first one is to trace the path of reactants. So we for some chemical reactions, we can't see when they're happening and um we can't tell um what's going on and when it's happening because it's not happening in front of us directly. Like for example, if a a chemical reaction inside of a plant, we don't know what's going on. We don't know what the reaction is. So if we replace one of the reactants with a radioactive isotope then we can trace it. So basically for example if I um if I had a plant okay and this plant um it takes up magnesium salts from the soil. Okay. So if I wanted to know what happens to the magnesium salts that it takes up from the soil and I wanted to see how what happens where does it get taken up when how fast does it get taken up um or used up in the reaction what I would do is um the magnesium salts in the soil I would replace them or not replace them I would add a couple of radioactive isotopes of magnesium salt this does not affect the chemical reaction at all because chemical reactions they're only between the electrons like it's only the electrons around the nucleus reacting with each other. When I add a radioactive isotope isotopes of the same um element, they have the same amount of electrons, same amount of protons. The only difference is the amount of neutrons. Neutrons are in the nucleus.
So they don't affect chemical reactions at all because chemical reactions don't have anything to do with the nucleus.
Only with the electrons, they only react with electrons. So if the magnesium salt if some of that magnesium salt I add a bit of uh radioactive magnesium salt um this magnesium salt the radioactive and the stable would go up through the roots of the plant and they would go up through the stem and then they would go to up to the leaves and in the leaves they would um you would they would get absorbed. So um if we had a gaja miller counter which um in last week's video I said um can detect radiation. If I if the gaja miller counter only detects radiation in the leaves that tells us that um only the leaves take up magnesium salt. The stems don't the flowers don't. The the roots only transport it. But uh the ones that actually absorb the magnesium salt is just the leaves. How did we know that?
Because the magnesium salt, the uh radioactive magnesium salt that was absorbed by the leaves um gave out radiation and that radiation was detected by the gaja counter.
Um it also uh because the we can use the gaja counter to calculate the rate of the radioactivity. So we can calculate how fast the leaf the leaf absorbs um u magnesium salts the radioactive magnesium salts and um we can also find out when it was used. We can find out if the magnesium salt stayed in the leaves a bit then it got absorbed or if it got absorbed immediately. We can find out um when exactly it was used. There's also other uses for tracing or uh or using radiation to trace. You can use it in crime scenes. Like for example, if um you have a like huge amount of money and you're scared it would get stolen, you can put a bit of radiation on top of the money. Um so if it gets stolen, you can detect it. And um you can also like for example, if I have um let's use the plant example again. If I have another plant, right? And this plant, I put it in two different types of soil.
I put like half of its roots in one in one part of soil and the other half of its roots in another pot of soil. And I wanted to see which pot of soil it takes up more. I would add one type of radio of um radioactive isotope like for example magnesium salt. I would put a bit of magnesium salt. Um, I I would put a bit of radioactive magnesium salt in this pot. And then over here, I would put another element that and this element, this radioactive isotope of this different element, um, it doesn't even have to be a different element as long as it's a different isotope. The reason why it has to be a different isotope, a radioactive isotope, is because, um, if it's a different radioactive isotope, that means it releases a different type of radiation.
And um there are ways like in last week what I said uh there are ways to be able to tell which type of radiation you have. So if I have one isotope over here and another isotope over here and they both release different types of radiation um and the gajia counter detects like a certain type of radiation let's say the magnesium salt the radiation that the magnesium salt gives out and it detects it in the entire plant. um and it doesn't detect any of this type of radiation that means it only takes up from this side and so on. Like for example, if I have uh if this was water, if this water was red and this water is blue and the plant only took uh and the water and the plant was only red, that means it only took up um red water. If it was blue, that means it only took up blue water. If it was purple, it took up from both. So using two different types of radioactive isotopes can tell us um how much of a reactant it's used and also which uh which reactant it's used.
So those are all the ways uh you can also use it in water pipes but um those are are most of the uses for tracing or tracing the path of reactants using radiation.
Um another way is to measure thickness.
Like for example, if I have um if I have a piece of paper and um if I'm a company that produces pieces of paper and I want the the the pieces of paper to all have this the exact same width.
What I can do is um alpha particles they get blocked by pieces of paper. So I can put for example a radioactive source over here and then every single paper I produce I can um put it over here and then put a gajger counter behind it. If the gajiller counter detects any alpha particles um that means that the paper is too thin. So they can adjust the settings in the I can adjust the settings in my factory and the paper will I'll make the paper thicker um so they all have the same thickness. for example. But uh we can use radiation to measure the thickness of um something you're producing that you want everything to be the same thickness. For this, we usually only use alpha or beta particles just because gamma will never be blocked by anything.
So it would be pointless to use gamma.
Third way is in radioactive dating. So um when we find old bones for example in the ground or when archaeologists like find old rocks or anything really old, how can we tell that how old it is? Like sometimes you'll hear and know this this rock is like a thousand years old or this um or this skeleton is 100 years old. How do they know that it's this amount of years old? How did they know?
They weren't around obviously at that time. And so how could they tell?
One of the methods that they can use is radioactive dating. So um the most common u radioactive particle that they use for this is carbon dating or they use carbon 14 and when they use carbon 14 it's called carbon dating. Basically um how does carbon 14 come to exist? Uh radiation from outer space. So this is earth. Radiation from outer space enters earth. Okay. And this radiation when it enters Earth's atmosphere, it converts nitrogen into uh C14 which is an isotope of carbon. Carbon 14, it's an isotope of carbon. So when the nitrogen gets converted into an isotope of carbon, this carbon is a very unstable isotope.
It's radioactive. Okay? And and um we said the radioactive particle is a particle that's ready to release radiation to stabilize itself. The type of radiation that C14 releases is uh beta particles. Okay. So C14 is always releasing beta particles to stabilize itself. Now because now C14 is in the atmosphere, um plants for example, plants take in air from the atmosphere.
Um these plants begin to take in carbon dioxide which they need for photosynthesis. This carbon dioxide has a small amount of C14 in it. So the plant takes up a small amount of C14 and this C14 it starts to decay in the plant. Okay? So because all radioactive particles they're slowly decaying.
Each particle decays at a different rate like some decay faster than others. Um for example C14 decays very slowly. It has its half life is maybe 5,730 years like around that much. Um, but when it takes up carbon 14, this carbon 14 is going to decay slowly and um and the plant is going to continue taking up carbon 14. So every time a bit of carbon 14 decays, the plant takes up more of it. So um the carb the amount of carbon 14 in the plant is equal usually to the amount of carbon 14 in the atmosphere.
Okay? And this is important for later.
So in the plant while it's living, it has the same amount of carbon 14 as the carbon 14 in the atmosphere that's naturally present. So when the plant dies, okay, um when it dies, uh it's not going to be taking up any more carbon 14 cuz it's dead. It's it doesn't need to make photosynthesis and it's not it doesn't need to perform photosynthesis.
Doesn't need to make any food because it's dead. It's it's dying. So, um, when it, uh, when it's dead, that means that, um, it still has carbon 14 in it. Okay?
And the carbon 14 in it, it's going to continue to decay normally as it usually does. But now, because the plant is dead, it's not going to be getting replaced anymore. So, um, if, for example, there was 9 g of carbon 14 in the atmosphere, in the plant, there would also be 9 g. After the plant died, this 9 g would just continue to decay and decay and decay.
Okay? And um let's say uh a thousand years pass, okay? Or 100 or 10,000 years passed. When 10,000 years passes, for example, and and this the the like remains of this plant was found. Okay.
um the scientists could measure how much carbon 14 is left in this plant. Okay, so um they know how much carbon 14 is in the atmosphere because they can just measure the amount of carbon 14 in the atmosphere. So they know that before the plant died the carbon 14 in it was let's say approximately 9 g. So they know that in the beginning we had let's say 9 g and then after the plant died ever since then it just been decaying and decaying and decaying and let's say when the scientists found the the um plant it only had 1 g of C14 left because those 9 g just kept decaying until they reach 1 g only. So um because they know the half life of carbon 14 they can tell that let for example it took it two half lives passed for it to get from 9 to 1. There are ways to calculate it. So they can calculate how long it took to get from 9 g which is the amount in the atmosphere to the amount they have right now. And this time is how long is is how old the plant has been dead or how long the plant has has been dead which means how old the plant is. So this is really useful because um it helps um it helps scientists figure out how old some stuff is other or otherwise they wouldn't be able to find out.
Now um before uh we used to only be able to date materials. When I say to date a material that means to say how old it is or like figure out how old it is using carbon dating or radioactive dating. So, they could only date materials that are up to 10,000 years old. Okay? But um and they had to have at least one gram left of carbon 14. If carbon 14 decayed into less than 1 g, it would be very difficult for scientists to be able to find how old it is until there was new techniques um invented. One of those new techniques was um in a lab in a radiocarbon accelerator lab. Um it's in Oxford. This lab, okay, it has this ion accelerator.
This ion accelerator, what what it does is that it shoots out carbon 14, carbon 13, and carbon 12. Okay, these two are stable. This is the unstable one. This is the one that's going to decay. This is the one that's radioactive. So, it shoots it out into a magnetic field.
Okay. So, this really powerful ion accelerator, it shoots them out at very high speeds. So, um carbon 14, carbon 13, and carbon 12 are all being shot out at very high speeds. Now, carbon 14, it's going to deviate. Deviate means that move away. It's going to move away from carbon 12 and carbon 13. That way we can get um we can get every single bit of carbon 14 that is in the um material that we're trying to date. So every single small particle of carbon 14 we can be able to get it. Without the iron accelerator we wouldn't have been able to get every single particle of C14. But now with it we can which means we have um a greater amount of C14 to test which means that um we can we can date materials more accurately and we can date them up to a 100,000 years and only a few like milligrams are required not even a whole gram anymore. So this is um this is what the ion accelerator helped us achieve.
So uh carbon dating can be used to date like for example large pieces of wood like furniture or stuff like that. Uh charcoal it can date charcoal. Um it can date um pete. Pete is a type of soil. Okay. So, um, so, so to be able to tell how old like a certain type of soil is, they can use carbon dating bones, like I said, and, uh, papyrus skulls.
Papyrus skulls are like those old pieces of paper that come from like usually from ancient Egypt. The like really old pieces of paper that are like brown and wrinkly. So, these are all the things that carbon dating um, can or these are all the things that we can use carbon to date.
And uh the equation that I was talking about earlier that can calculate how long it took um how long how much time passed to get from the original amount that was present in the atmosphere to the present amount you have today is this one. A n is equal to a o over 2 ^ of n. A N is the um final amount the amount after a certain amount of half lives passed. Um so uh a n is the final amount. The amount that you have right now like if I found the bone the amount of carbon 14 in that bone is the final amount. Okay? And then initial amount.
Initial amount is the amount that was in the atmosphere in the beginning before it started decaying.
And then n is the number of half lives that passed.
Sometimes they won't give it to you as amount in the atmosphere and amount that you found right now. Sometimes they'll tell you like uh different questions like for example you can say um uh this material or this plant um had originally like 320 g for example of carbon 14. It now has 4 g. How many half lives passed and you would just need to calculate for half lives and so on. So just different questions. This is the equation we use.
This is just a very simplified form of the equation in math. And this one's easier because it will give you whole numbers which is physics is not trying to test your calculation ability. So it wants whole numbers. It just wants you to understand how to get a halfife. So this is the best one to use for physics.
Okay. Fourth reason or fourth way we can use radiation is in medicine. So um uh radiation helps specifically a lot as a treatment for cancer. So what's cancer? Um it's when cells in your body start to multiply rapidly and um they can't be controlled and that when the cells keep multiplying and multiplying um a lot uh and in a very uncontrolled way it becomes harmful to the body. So radiation can a very high dose of radiation can kill cells. Okay. So um for a person with cancer this can be useful to you can use radiation to kill the extra cells in the person's body.
But the problem with this is that um we have healthy cells um in our body and most of our body cells are healthy. If a person has cancer some of those body cells have turned unhealthy. they've started to multiply and cause the cancer.
Um, and radiation can't tell the difference between healthy cells and cancerous cells, the ones that keep multiplying uncontrollably. It can't tell the difference. It will just kill any cell it sees. So, the problem with radiation is it will it will kill the healthy cells too. And um, even worse, it will cause some of the healthy cells to turn into cancerous cells. So after a certain amount of years for example um some healthy cells that have been under the influence of radiation they will start to become cancerous and start to divide and uh become uncontrollable again. So for a person with um cancer radiation is only used as a treatment for cancer in like the worst stages when uh when you can't remove it by operation. some types of cancer um you can remove them by operation, you can undergo surgery, you can use chemotherapy. Um when all of those don't work, that's when you bring in radiation. So for a person who has to undergo um who has to go through radiation therapy at that point it's usually um they're usually in very like critical condition and they're basically deciding that either um they die right now or like in a very short amount of time or they go through radiation therapy um they live for a couple more years before the healthy cells turn cancerous again and they die in like let's say 10 years instead of 10 months.
So what they're doing is just buying more time. And um for someone who's already very sick, this is a really good option for them. So radiation can be used as um to as a treatment for cancer sometimes.
Fifth reason or fifth use of radiation is uh as a luminous scale. So um I brought this up last week too. Um, some materials are fluorescent, uh, so they glow in the dark. Um, some radioactive materials can glow in the dark. So, some of these fluorescent materials, um, we can put them on exit signs, we can put them on watches, we can put them on numbers, on traffic lights, all all these things that need to glow in the dark. For example, on an exit sign, um, this exit sign in the dark, it's going to glow. So, that way, we don't have to use any electricity or anything. we can just coat it with a fluorescent material and it's going to start to glow and show people where the exit is and in watches too and other um other uses too. So um back in the 1920s when people first started using radiation as illuminate as a fluorescent material to like illuminate um some objects like for example watches. the workers that were making these radioactive watches that would glow in the dark, they didn't have um a lot of knowledge about uh safety regulations or like how to be safe um when dealing with radiation. There wasn't really much knowledge about radiation at all at that time. So because of that they used to um lick their brushes to um like fix the bristles together or like uh like fix the paintbrush. So they used to lick their brush brushes and on these brushes were the fluorescent materials the radioactive materials that they would paint the signs or the watches with. So because of that they were basically uh putting radiation straight into their bodies and um and that radiation that entered their bodies started to cause um cancer in their in their bodies especially blood cancer and um it would start to um kill off some of the cells in their bodies.
So a huge amount of these uh workers, almost all of them, they died from bone cancer or anemia um which is when you have very low iron um and other forms of cancer just because of the fact that they didn't know that um radiation was dangerous to lick off your brush. And even some scientists that would work with radiation like Mary Cury and her daughter she was also a scientist they also passed away from uh different types of cancer due to radiation.
So even though it's used as a treatment for cancer in really um critical stages, it can also cause cancer a lot. So um that's one of the dangers of radiation.
And the final use of radiation is in food.
So um not a lot of people agree with this like some people agree some people don't but radiation is used for um food irradiation and insect control. So the problem with most foods is they spoil really quickly and the reason why they spoil is because they have certain types of bacteria and insects um and enzymes on them and all of these things they cause the food to spoil. So when you put radiation over let's say strawberries or food crops, any type of food, when you put radiation over them, it kills all the bacteria and insects and enzymes that cause the food to spoil. That way um uh you can preserve food for longer and and um um it won't spoil for a very long time. And when you add when you put radiation on top of food, this food become is called now irradiated food. So irradiated food is just food that um has has been sprayed with radiation to kill all the bacteria and enzymes that cause it to spoil. So um and even another another way is the insects that come on uh food when radiation comes on them it might not kill them but it will cause them to to become sterile. Sterile means you you can't have children anymore. So if this insect let's say if these let's say 200 insects can't reproduce anymore um after a certain amount of years they'll all die out naturally and then they just won't be a problem anymore. So radiation can also cause um hysteridity.
And um another reason, it's not um it's not mentioned a lot, but it's also used in airports to like find explosives in your luggage. Like when you when you put your suitcase on the like belt and it goes through that scanner thing, that scanner uses radiation to look inside your bag and find if there's any explosives.
Now, even though radiation has a lot of uses, it's obviously very dangerous uh especially to the human body.
So, one of the there's like four main dangers of radiation. One of the uh one of them is that extremely extremely high doses of radiation or radioactivity, it can cause you to die immediately. And we're talking very high doses like um extremely high. it they can cause you to die immediately or they can cause you to die within a few weeks um if it's a slightly lower dose and if it's um for smaller amounts of radiation they can cause the main cancer that they cause is leukemia. Leukemia is blood cancer when your blood cells start multiplying uncontrollably.
So um for a lower dose of radiation um it can cause leukemia mostly which is the main type of cancer it causes and it c it can cause other types of cancers.
Leukemia takes like around 2 years to um to like appear in your body uh if you've been exposed to a lower dose of radiation takes about 2 years. Other types of cancer can take like 15 years or more even. So um the main cancer caused by radiation is leukemia.
in at the end of World War II in Japan, um two of its cities were bombed by atomic bombs in like within 3 days of each other. And the people or the survivors of those cities, most of them had uh obviously a lot of them had a lot of cancer because they were exposed to a huge amount of radiation and um most of them had leukemia. Like the ratio was like 6:1. Like for every patient who had cancer, there was six others that had leukemia. So um leukemia is the main type of cancer that radiation causes.
Uh another thing is radiation can cause genetic aberrations. So genetic aberrations, genetic aberrations is when your so your entire body um the way you look and the way you look and the way your body functions and everything is decided by your genes. Your genes are basically the instructions to everything happening in your body. So when radiation is can enters a human body, it can cause um some of these genes to mutate or change into a different form or uh and this different form is it's like a broken form of your old genes. So it can um and these when these genes start to mutate when they change into something different that's called a genetic aberration. this genetic aberrations um um they cause diseases, they cause early deaths like you can die really young because of it. Um they can be passed down to future generations because at the end of the day um when you're having children, you're giving them your genetics. So, um, these faulty genetics, these, uh, broken genetics that are that were ruined by radiation, you're going to give them over to your children and that will cause them to be sick also, even though they they would probably never have been exposed to gen to radiation. They can also even radiation can also even destroy your genes like completely. So, um, that's one of the dangers of radiation to to the human body.
And then um like with most cancer patients who get exposed to radiation or radiation therapy um radiation can damage hair. It can cause you to lose your hair and it can cause like soores to form on your body. Um so sores are like painful spots on the body. So it can cause like um these spots that are really painful to you to form on your body. It can cause you to lose your hair and it usually takes a very long time to heal. That's why we see um most of these symptoms in cancer patients who have went under radiation therapy.
So when radiation enters the body right um we just said about all the dangers of what can happen but what actually happens when it enters. So when it enters your body uh radiation has energy. So the energy inside the radioactive particles um the I mean the radiation particles the energy inside them when it enters your body it gives that energy to the body tissues. So the cells and tissues in your body it just gives the radiation gives the energy to your body tissues.
So um to find how much radiation you someone absorbed like for example in Japan right someone who was in the city like in the middle of the city that was bombed by an atomic bomb is going to be is was going to be exposed to more radiation than someone two cities away.
Yeah that's that person two cities away could have also been exposed to radiation but it's a much much less amount than the person who was in the city that was bombed. So how do you know how much radiation was absorbed by each person? You find something called the absorbed dose.
The absorbed dose is the amount of energy absorbed by a body.
The amount of energy absorbed per um unit mass of organ or tissue.
So um it's the amount of energy that was given by the radioactive particle to your body tissue and that amount of energy is per the mass of the tissue or organ that it gives energy to. So the unit of this is either jewels over kg because remember it's amount of energy.
energy is measured in jewels over or per the mass of tissue mass is measured in kg. So the unit for the absorbed dose can either be jewels over um kilogram or it can be gray gray like the color. So um uh it can unit for absorbed dose is gray which is abbreviated as gy. So um we can either use gy as as a unit for absorb or jewels over kg. We can also use rad. So um one gray is equal to one jewels over kg. But jewels over kg and gray are equal to 100 rads.
So if you're going from rads to jewels over kg or rads to gray or vice versa, there's going to be a bit of conversion because um gray and jewels over kg are interchangeable. You can use any one but rads and the other two you have to convert um you you either multiply these two by 100 or divide the rads by 100 to get the value in the other unit.
Now um I've mentioned another unit for radiation before the BQ right BQ measures the rate of radiation how fast a radioactive source is releasing radiation okay gray for example or J over kg or um or rad these three they all measure the absorb dose how much energy um your tissue absorbed so they're two different things uh BQ is how much radiation a source releases.
Sorry. BQ is how much energy a source and um these three units are the amount of energy your body absorbs. So they're are two different things.
Now um radiation is everywhere. Okay. As a human being living, you can never be completely free of radiation. You at some point in your life, you absorbed a very small amount of radiation just from your surroundings. Okay. Um, so the average dose in a lifetime from natural sources, like you've never, you don't work in a nuclear power plant, you haven't been near radiation, you haven't been near any atomic bombs, any any unnatural source of radiation, you haven't been near it, you've just been living normal life. The average dose is 10 rads. Okay, 10 rads of radiation.
Um in for example at the end of World War II in Japan when they were bombed the people were exposed to several hundred rads. So like um above 100 rads of radiation and that caused like almost 4 to 10 cases of leukemia per 10,000 people per year. So every 10,000 people at least four to 10 of them had leukemia which is a huge amount compared to the normal amount of leukemia um patients without the atomic bomb. So um most normal people are exposed to 10 rats.
Now um if if someone was was exposed to alpha radiation and someone was exposed to beta radiation and someone is exposed to gamma radiation. Okay. Um uh it's the one who was exposed to alpha particles. Even if they were exposed to the same exact amount, if they're exposed to 10 rads of alpha, 10 rads of beta, and 10 rads of gamma, um even if they're exposed to the same amount of radiation, the one who was absorbed to alpha is going to be hurt more, is going to be harmed more. That's because um of how much each one ionizes.
So alpha ionizes way more than beta and gamma. Alpha ionizes 10^ 5 per per um cm.
Beta ionizes 10^ 3 ion pairs per cm and gamma ionizes 10 per cime. So we can tell obviously that alpha ionizes the most out of any of these ones. Which means the more you ionize, the more harmful you are to the person. So the person who absorbed 10 rads of alpha radiation, they're a lot more sick than someone who absorbed 10 rads of gamma radiation. So how do I know how much how how much radiation a person truly took in? Because um if I tell you I I took in 10 rads of radiation and I don't tell you the type of radiation, that doesn't tell you anything about how sick I am, okay? Or how harm harmed I am by the radiation because they all have different effects. They all have different amount of harm. So we have something called the absorbed the equivalent dose. So the equivalent dose the equivalent dose is um the the true amount of how much radiation you you took in. So even though you took in the same amount of the three different types of radiation because alpha harms more than beta does and more than gamma does um to get uh to get the amount of how much radiation truly affected you uh we multiply them by a constant. So we multiply the absorbed dose the amount of radiation you took in we multiply it by a by something called WR. This WR is called the radiation weighing factor.
And this radiation weighing factor is different depending on the type of particle. If I had 10 kg of feathers and if I had 10 kg of rocks um and I threw them at someone's head, the rocks are going to hurt a lot more.
Why? Because um rocks have are a lot denser. And even though they're the same amount, um it's going to hurt. The rocks are going to hurt way more than the feathers did, even though they were the same mass. This is the same, um concept.
Alpha ionizes a lot more, which means it's going to harm a person a lot more.
So WR for beta and gamma particles.
Okay, for beta and gamma particles, WR is equal to 1. Okay. So, um the any absorbed dose of gamma or beta, you just multiply by one. So, what you what you absorb of gamma particles and what you absorb from beta particles is what you're actually being harmed by. And then um alpha particles their WR is equal to 20. So, anyone who absorbs alpha particles um alpha particles are 20 times more harmful than beta and gamma particles. And also um when neutrons are just floating freely, okay, they're not attached to a nucleus, they're not in an atom or in a nucleus or in an ion. When they're just floating freely, um these neutrons become radiation. So these neutrons are considered radiation if they're just free floating. So um neutrons because they're also considered radiation, they also have a wing factor. They also have a WR. So um for neutrons WR is equal to 5 to 20. So it depends on how fast the neutron is. Okay.
So if it's a really fast neutron it might have let's say you might the WR might be 20. If it's really slow neutron WR might be five. If it's in between it might be 10 for example. It depends.
Okay. Depends what the speed of the neutron is.
But for alpha it's 20. The WR is 20. So any absorbed dose of alpha you multiply by 20. And for alpha and for beta and gamma it's one. So whatever what whatever the absorbed dose of alpha and gamma is that's what you actually are being harmed by. That's what the actual um dose is.
Now um we can use radiation as a power source as a source of um energy or or not energy as a source as a source of power. Okay. So that's the whole purpose of nuclear power plants. They take advantage of radiation. So how do they do it?
Um basically radiation has a lot of energy inside it. Okay. And when this radiation is uh blocked by any type of matter the when I'm when I say radiation I'm talking about um alpha beta and gamma.
So um alpha, beta and gamma when they are blocked by something the energy when they are coming at something and they get blocked the energy that is inside them is converted to random kinetic energy.
Random kinetic energy is just heat. So the energy that was inside these particles when they are blocked by something the energy inside them is converted to heat. The problem with this is this heat is first of all very hard to control and second of all it's very small amount like it's it's very ne negligible amount you can't even feel it. So um radiation alpha beta and gamma is not a good source of um heat for a nuclear power plant. So we have to use another type of um energy and this is fision. So fision is just um when a really big nucleus it combines with a neutron and when when it when it's attacked by a neutron it splits into a lighter nucleus a two smaller lighter nuclei. Okay. So any um so a fision is just when a really big nucleus is attacked by a neutron and splits into two small nuclear. Now we can use fision to power a nuclear power plant and the reason for this is because it generates a lot of energy and this energy is in the form of heat. So fision generates a lot of heat and also um uh we can control fision. That's why we can't use fusion. Fusion is just this opposite without the neutron. It's when two lighter nuclei combine to form one big one. Fusion is very hard to control.
Okay? We can't control it the same way we can control fen. So um in nuclear power plants um until now we've only ever been able to use fision as a source of as a source of fuel for nuclear power plants.
Now um basically there's two types of vision.
There's spontaneous vision.
Spontaneous means it just happened randomly. Okay? It wasn't triggered by something. Spontaneous fision is just when a big nucleus just randomly decides to um to uh split into two small um nuclei.
Why did it split into two small nuclei to stabilize itself? Because fision fision happens with radioactive materials. So when a radioactive material radioactive material are materials that are unstable they need to stabilize themselves. How do they stabilize themselves? By releasing radiation.
So in in fision it's when this really big unstable particle it splits into two and releases radiation. What's the radiation that it releases? It releases a neutron.
So um when when uh when in spontaneous fision when fision just happens on its own without any influence by anything else. In spontaneous vision, a big nucleus, a big unstable nucleus split into two to stabilize itself. And while it was doing that, it it released radiation in the form of one neutron. And remember what what I said earlier, a neutron floating freely, not attached to an atom or an ion or nucleus or molecule or anything, just floating freely on its own is radiation. So when the big nucleus splits into two and releases the neutron, that neutron is on its own.
It's a free neutron which means it's considered a type of radiation. Now in non-spontaneous fision, non-spontaneous vision is when it was triggered by something. So um non-spontaneous vision is when you have a big particle. Okay, this big particle was attacked by neutron. Okay.
And when it was attacked or bombarded, bombarded just means like attacked by a neutron. When it was bombarded by a neutron, it caused it to split into two lighter nuclei. And when it split, it released radiation again, which is another neutron. So, uh, nonspontaneous is the type that is used in nuclear power plants.
non-spontaneous which is the um which is the one that we can control because we can add neutrons to radioactive particles. When we add neutrons to radioactive particles, it causes them to split. It causes them to to release more neutrons and then those neutrons split up more um heavy nuclei and then those heavy nuclei release more neutrons. Those neutrons split up more nuclei and so on so on so on. um and if we can control the amount of nuclei that means we can control the entire fision reaction. So um nonspontaneous is used in nuclear power plants. Now what usually happens in nuclear power plants is we have a radioactive material. Usually we use uranium when uranium occurs naturally or we use plutonium.
Plutonium is man-made. Okay. So um I had this uh radioactive uh nucleus. Okay.
It's very big. It's very heavy. It's very unstable. It wants to stabilize itself. So this um uranium the thing about fision that occurs naturally is it happens very rarely. Fision releases a lot of energy when it's when it's unlike alpha and beta and gamma. Um when fision happens when it releases radiation it releases a lot of heat energy at the same time. So because it releases a lot of energy um we use it in nuclear power plants. But the problem with natural fision is it happens very rarely. It's um it's any by chance that a big nucleus decides to split using fision. It's very rare to happen. So once they once they figured out how to control it and make it happen that way they got a way to produce um a lot of energy whenever they wanted. So how did they do this? They had a radioactive particle. Okay, this radioactive particle, it could in 100 years split into two and release a neutron or it could tomorrow split into two and release a neutron. We don't know. But we can make it split into two and release a neutron. How do we make it? We just um we just uh put a neutron. We can add a neutron to it. This neutron when it attacks the uh big radioactive material, this radioactive material splits into two. Okay? And while it's doing that, it releases another neutron. Okay? And then this neutron um it can it doesn't just have to release one neutron. It can release multiple actually. Um so when it releases neutrons um these neutrons then bombard other molecules, not molecules, they bombard other heavy nuclei. So when they bombard other heavy nuclei, those also split into two lighter ones and also release um neutrons while they're at it. And then when they release neutrons, those neutrons then go on to split up more um heavy nuclei and then when they split up, they also release neutrons. So this is called a chain reaction. Okay, this is what happens in nuclear power plants inside the core. Okay, I'll explain now how it works. But inside the core, which is where this reaction happens, which is where the fision reaction happens, um a chain reaction happens. And in fision, we release three things. We release um energy as heat and we release a lot of energy. And this energy is what powers the entire power plant. and we release smaller nuclei.
We split into two smaller nuclei. Okay, that's the second thing we release. And we also release free neutrons which are radiation.
So these are the three things that we release during fision. Neutrons, smaller nuclei and a lot of heat. Okay, that's why fision specifically fision is the reaction that is used in nuclear power plants because then the neutrons that that that um they produce can be caused to control more reactions and um it gives a lot of energy.
Now a file some substance uranium and plutonium which are just two radioactive elements. These two are called file file substances.
These are just very big um very big nuclei that give off neutrons when they split in half. So this is the um file substances are just what we use to um uh make fision. So these are just the heavy nuclei in fision.
Now we can control uh fision by doing uh couple different things. So if we increase the concentration of radioactive materials that means I increase the amount of uranium I increase the amount of plutonium I increase the amount of file materials if I increase the concentration that means I'm going to increase the rate of fision and fision is going to occur more fre fre fre fre fre fre fre fre fre fre fre fre fre fre fre fre fre fre fre fre frequ frequently why because the more heavy nuclei for neutrons to bump into, the more they're going to split, the more they're going to release energy. Um, and also if I increase the quantity of neutrons, I can add more neutrons. I can not just the ones that are produced by fision, I can also add more neutrons um from myself. And uh those neutrons can also speed up the rate of fision. And also if I decrease the speed of the neutrons.
The reason why decrease is because for example if you're walking through a classroom and you're handing out papers to each table. If you're going slowly you can give a paper to each table. But if you're sprinting through the classroom you're going to miss some tables. You're not going to be able to give a paper to every single table. So for neutrons, neutrons the whole purpose of them in fision is to split up heavy nuclei into lighter nuclei. So if they go more slowly that means they can attack more um heavy nuclei.
And um all of these factors if you increase concentration, if you increase quantity, if you decrease speed, all of these cause the rate of fision, the speed of fision to um to become higher.
And when that happens, more energy is produced. So, so not only can we control fision, we can also control how much energy is produced by fision.
Like I said before, fusion, we can't control it for now. So, um it's not an option to power nuclear power plants anymore.
Now, um what happens if fision goes uncontrolled? If we don't control the amount of neutrons there, if we don't control um uh everything there, if we don't control it, uh explosions happens.
So in nuclear bombs like for example atomic bombs that were um um the bombs that were released on Japan at the end of World War II, those were uncontrolled fision. They caused explosions because the fision was uncontrolled. um it's it's the heat got so um high that it exploded. So uh uncontrolled fision is used in nuclear weapons such as atomic bombs or hydrogen bombs.
Now um for example if a uranium um a uranium nucleus it's uh very big right? So we can split it into different types of smaller nuclei. So we can split it up into zenon which is a type of um radioactive particle too. Just a smaller radioactive particle that comes from uranium. We can split it up into radian.
We can split it up into any type of combination um for uh any combination of radioactive elements that can come from uranium cuz uranium is so big. Okay.
It's like if I have a bag of different colored candies. I if I put my hand in, I can either get one yellow, one one red. I can get one blue, one green. I can get one green, one red. I can get one green, one yellow. There's so many different combinations of elements that can be produced from splitting up uranium into two. So there's a lot of possible byproducts. Yeah, every single time I'm producing only two. every single time the nucleus is splitting into two. But those two can be different types of elements. It can be um any any type of element that's in uranium. So there's many possible byproducts.
In radioactive decay, for example, radioactive decay and alpha alpha um beta uh gamma uh there's only one type of radiation that can be produced which is alpha beta or gamma depending on the on the on the reaction. So, so if if you know that this radioactive isotope only under goes alpha alpha um decay, you know that the radiation that's going to be produces alpha. You know that the radiations that's going to be produced if it under go better decay is better.
If it releases gamma waves, you know you're going to get gamma waves. You're not going to get beta or alpha if it releases gamma gamma waves. Unlike with fision where you can get a lot um a lot of different combinations of elements depending on what it's split into.
Now radioactive decay it does release heat when when when um when it's when like let's say um radioactive isotope um decays into alpha particles or beta particles or gamma waves, it does release a small amount of heat, but it's so small that it's negligible. And it's usually so small we can't even control it. So fision is the only one we control. Now what happens in a nuclear power plant? In a nuclear power plant we have um a reactor. Okay. So the reactor looks something like this.
Okay, the reactor looks something like this. This reactor is it has um the elements that we put in the file materials the uranium or the plutonium usually they're put in in the form of rods. So the there's going to be like rods of file materials or radioactive materials in here. By rods I mean like they almost look like metal like they're in solid form. And also from those rods we have another type of rod which is called a we have another type of rod which is called a control rod. These control rods um they control the amount of neutrons in there. So these control rods are the reason we can control fision reactions.
So um uh the radiation the radioactive particles and the control water in this tube and also in this tube is a coolant.
So this coolant is usually either a gas or a liquid water. So it's either water or gas. So um there's also liquid inside here.
Okay. And then um this tube that's outside it's goes into a bigger tank.
Okay. So, this is um usually what the inside of a power plant looks like.
So basically this is the core right and also usually this part of the of the tank which is like this part that has the um tank and the core it's usually in its own section because of the fact that this is where the fishing reaction happens. So it has to be progressive.
So um this part is the core. This is where the reaction happens. Inside the core we have the coolant which is water and we have control rods and we have the facade materials. Inside this tube we have at the bottom here we have water or condensed coolant and so do we have in this tank. So basically what happens is this core um the fish the fish reaction happens and this fish reaction when it happens it releases a lot of heat. So this coolant inside this liquid inside the water the blue lines um they get extremely extremely extremely hot. So this area um this tube okay all of it becomes extremely hot. Okay. Now because it becomes extremely hot. Um it goes into this tube.
This tube is filled up. This tank I mean this tank is filled up with water. Okay.
So this water when when the when this tube becomes very hot when this tube over here the tube that's inside it when it becomes very hot it causes the water inside of here to evaporate. It turns into steam. So when it turns into steam, the steam exits through this tube. Okay.
So this tube um this is all steam. Okay.
Exiting the tube and the steam um the steam that was um evaporated from the water inside this tank that was boiled by the very hot um tube in here. This steam is used to power a wind turbine.
Not a wind turbine, sorry, just a normal turbine.
So this turbine is uh attached to a generator.
So the steam when it enters it causes the turbine to turn okay turn without electricity without anything. It's just the steam turning the wind turbine. And when it turns the wind turbine it causes the generator over here to generate power. Okay. Usually let's say in the form of electricity for example. So this is the generator.
Okay. And then the steam continues.
Okay. After it's done with the wind turbine, it enters this tank. Now, inside this tank, um this tube is the opposite of this tube. This tube is um it has it's a condenser. Okay? So, it has very cold water inside it. This water inside it um it's very cold, which means that it's um it cools down the steam that's entering this steam that's entering it cools down. And when it cools down, it condenses back into water. So it condenses back into liquid. And then this liquid enters this tube. Okay? And then goes back back into the original tank it came from. And um and it makes up the water that's in the tank. So this the water in the tank then gets evaporated um powers the wind turbine.
The wind turbine powers the generator and produces electricity or energy or power whatever in whatever form we need it in. And then the steam enters the the condenser area it gets condensed into water again and the cycle continues. Now the reason why we have a separate tank of water in here is because this water that's inside the core this this water over here that surrounds the radioactive materials and surrounds the control rod.
This water is very radioactive. Okay, which means that um it's very unpredictable. It's very dangerous. So this um coolant, this water inside here is called the coolant. Okay, so this coolant is usually very radioactive. So that's why we need another separate tank of water. The water in this tank is is not radioactive. It's safe because it never actually touches the this tube of um of coolant. It never touches the radioactive water. So, it doesn't become radioactive because they're two separate tubes. It's just their temperature that's um making this evaporate into steam.
Now, um there's a lot of reasons why we use um nuclear power plants and why they're a really good option. Okay, so there's three advantages and three disadvantages. Now one advantage of um of using a power plant is that um the only other option other than power plants is fossil fuels and fossil fuels.
Okay, fossil fues release three things. They release carbon mainly carbon. That's what they most that's what they release the most. They release carbon, they release sulfur and they release nitrogen.
So these are the three things that when we burn fossil fuels, these are the three exhaust gases that are produced.
So basically fossil fuels when they release carbon okay the problem with them releasing carbon is that um okay we have electromagnetic radiation electromagnetic radiation is just radiation in the form of waves you not particles waves. So radiation waves from the sun, okay, the radiation waves from the sun when they enter earth, okay, they um they go into earth and they get absorbed by earth. And when they get absorbed, okay, um when they get absorbed by earth, earth absorbs them, absorbs these radiation rays and then reflects them back at the sun, okay? At or back at Earth, okay?
outside of the atmosphere. Now, obviously because these radiation rays are coming from the sun, they're going to be very hot.
So um when we have carbon in the atmosphere, okay, when we have carbon in the atmosphere, um this carbon, if we have a very high amount of carbon dioxide or carbon and jeller, when we have a very high amount of carbon, um this carbon when the radiation comes to bounce back back at the sun, um it doesn't allow the heat from the radiation to leave. It allows the light ray to leave. It allows the entire ray to leave, but it doesn't let it traps the heat of the ray inside. Okay? So, because it's trapping all the heat of the earth inside of the array, it traps all the heat of the ray inside the earth. That means the earth gets hotter.
And when the earth gets hotter um that causes global warming, global warming is like um like the very cold areas start to melt. farm areas, agricultural areas become deserts. Um it's not a good thing at all. Okay. So fossil fuels they cause global warming.
Okay. And this all is called global warming is called the greenhouse effect.
Okay. So this is called the greenhouse effect. Now um fossil fuels they cause greenhouse effect. They cause global warming. They cause the earth to get hotter.
Now, um um in in nuclear power plants, nuclear power plants, they don't burn anything.
We're not burning anything. There's no um fire burning anything, which means there's no gases being released. All that's happening is just like radioactive reactions or radiation reaction reactions. So, because nothing is burning, there's no gases being released, which means we're not harming the earth um by releasing carbon. we're not causing global warming anymore. So fossil fuels cause global warming, but nuclear power plants, they don't cause it. So that's one of the advantages.
Another advantage is that um uh we said that uh fossil fuels release carbon, sulfur and nitrogen.
Okay. Now we talked about what happens when you release carbon. Now when sulfur and nitrogen get released, okay, when sulfur and nitrogen get released, when they when they get burned, okay, when they get burned, they evaporate into the air. When they enter the air, nitrogen and sulfur oxides are produced. So they join with oxygen and they form sulfur oxide and nitrogen oxide. When these oxides are produced, these oxides dissolve in rain. They dissolve in clouds in the raindrops and clouds. So when they dissolve in the raindrops and clouds they cause the raindrops to become acidic. Okay. So when the rain becomes acidic um that means that we have something called acid rain. Acid rain is rain that has sulfur oxide and nitrogen oxide in it and it's very dangerous. It can kill trees, kill forests, kill animals, cause people to become sick, poison lakes, cause fish to die. it's um very dangerous. So that's another consequence of fossil fuels that does not exist with nuclear power plants. Um now as the third and final reason is that fossil fuels are limited.
Okay, let's say one type of fossil fuel um is coal. For example, you can burn coal to generate energy. Coal is limited. You can run out of coal. We can run we can use up all the coal on earth.
But with uh nuclear power plants we have something called plutonium. Plutonium is what powers plutonium can be used to power um file reactions or fision reactions. So plutonium is a file material. Plutonium is man-made. We can make it if we run out of plutonium. We can make more plutonium. We can't do that with coal or with oil or with any other energy source that we that or with any other fossil fuel that we burn to um to produce um with any other fossil fuel that we burn to produce energy. Um those run out plutonium doesn't also fish um in in nuclear power plants they will eventually run out of fuel. Yeah, they will run out of uranium or plutonium, but they only run out once a year and we only have to refuel them once a year.
With fossil fuels, fossil fuels, we have to um um let's say it's a coal um we're using coal as the fossil fuel. We have to have hundreds of buckets of coal of coal every week.
Okay? So, we're using up a lot of materials unlike with nuclear power plants where we only use man-made plutonium once a year, which is a crazy difference. So, nuclear energy also does not need to be replenished that much.
Now, um those are all the benefits of um nuclear energy, but there's also disadvantages. Okay, it's um there's disadvantages to using radiation as a power source. So, one of the first disadvantages is that um is that it's very expensive. Okay, cost is very high. Okay, the problem with radiation is you need constantly protection. You need to protect um the workers working there. You need to protect the core. You need to you need the the entire building has to be made of made out of very thick materials very um um all the protective materials have to be replaced often because after a certain amount of time um even if you have like really strong radioactive even if you have really strong protective material especially for the workers working there even if their uniform is very thick and uh covered in very strong protective material eventually that that uniform will also be start to become radioactive um which means there that's also going to have to be replaced. All of this is super expensive um and takes a lot of money because you're constantly replacing uniforms. Uh buildings have to be incredibly thick and uh have a lot of resources. Um uh everything you have to be so careful you have to spend a lot of money just on pre preventing radiation from leaking out which means that makes nuclear energy very expensive.
Second disadvantage is the waste. Okay, with the with the radiation um we have eventually okay plutonium and uranium and any other file material they're going to get used up eventually right so um when they get used up we have to throw them throw them away and also the protective materials that have become radioactive we also have to throw those away right so when we throw them away um they're still radioactive, okay? They never truly become not radioactive. So the used official materials are radioactive and the used uniforms are radioactive. So when we have to get rid of them, we have to be very careful. We have to bury them very deep in mines. Um mines are like underground like tunnels.
We have to bury them in solid concrete concrete just to prevent the radiation from leaking out and um contaminating water.
For example, there's a lot of most of the water on Earth comes from underground. So if any water that's underground becomes radioactive, um that water first of all spreads. So people in other countries will will be affected by that radioactive water and um it will cause people to become sick. It's going to affect all people especially if the water gets contaminated. So you have to be very careful not to contaminate anything except especially the water.
Now the third disadvantage is uh people are scared of nuclear energy because there's a lot of very famous incidents um with nuclear energy. Like for example, like I said um at the end of World War II, two Japanese cities, Hiroshima and Nagasaki, they were both bombed by atomic bombs that released a lot of radiation. And um and um also another incident that happened is in Ukraine in a city um in Ukraine Chernobyl. Chernobyl had a very big nuclear power plant and an accident happened in that nuclear power plant. It the core in one of the core reactors in Chernobyl. it overheated and a fire broke out. And that fire caused one of the reactors to melt. And when the reactor melted, it released all the radiation and the file materials inside of it. And that was um that caused a lot of radiation to spread everywhere. Okay.
Um other countries, almost the entire continent of Europe, cuz Ukraine's in Europe, almost in the entirety of Europe was affected by radiation. People in Austria, they couldn't eat milk or sheep's milk or meat or products like that because the sheep in Austria had gotten radiation and had become unsafe to eat for a certain amount of time until that radiation decayed into a safe amount. So people from far away were were affected. Um some some people even passed away from it. uh people became ill and because they're such famous incidents also at the end of in Hiroshima and Nagasaki a lot of people not only died from the initial like blast but they also got very sick um a lot of people got cancer and leukemia and a lot of those people even if they managed to get away from Hiroshima cuz Hiroshima was bombed first and then 3 days later Nagasaki was bombed. So the people who had managed to survive Hiroshima and Nagasaki is close to Hiroshima. So they escaped to Nagasaki.
And then those people um also were bombed again 3 days later. So they got um so they were even more sick. A lot more people died from that too. And um they passed on those diseases to their children. So there's when you think of radiation um no one really thinks of it in a positive way or or in a um safe way like no one thinks of radiation as a particularly safe option even though we know logically that radiation can be made very safe. Okay the incident in Chernobyl um there's a lot of measures that can be put in place to prevent it from ever happening again. like we can use gas um as a coolant instead of water and when if we use gas as a coolant it will never allow the temperature to reach high enough to melt a reactor again. So the so what happened in Chernobyl is logically never going to happen again and um um the problem with this is people are very scared of radiation. So they're not going to accept nuclear power plants being built next to their homes. They're not going to accept nuclear waste being buried next to their homes. And um um they're also the most people believe that if if a nuclear power plant yeah it can be used for good reasons. It can be used to generate energy but it can also be used to build another atomic bomb and um it can be used both ways. So that's why people are very like they don't want to accept um nuclear power plants which is one of the disadvantages of it.
Okay. Uh that's all further explanation.
Now we can start the quest.
Okay. Disadvantages of nuclear energy. I was just talking about this. In case of failure of protective covering, radiation can seep through the environment. That's one of the issues.
We can't contain radiation. Nuclear plants pollute the environment. Um that's one of the advantages actually because it does not um pollute the environment. Halflife is very long.
That's one of the problems.
Most waste materials of um radiation, they have a very long halflife. Like for example, carbon 14 had 5,700 years.
That's like that's a crazy amount of time. So it's going to take a very long time for these um for nuclear waste to decay enough that it becomes safe. So you have to consider that also. So that's one of the disadvantages contribute to global warming. It doesn't. That's one of the things fossil fuels do. So nuclear plants are actually that's one of its advantages because it does not do that. And very large amount of fuel. That's not true. They only need to be refueled once a year.
Okay. Safety measures. Uh move with your hands. That's not true. You have to use gloves always or not gloves even. Uh you have to use um tweezers just so they don't come in contact with your skin or stay on your gloves. Pointing away from you. Yes, it has to always be pointing away from you in case anything happens.
Since radiation suits out, it's not coming at your face. Using your eyes only, it's best not to uh use your eyes when examining radiation or at least like use some kind of covering because if radiation enters your eyes, it can harm your eyes. Okay. So, and um should be locked up in a safe place. For example, a lead box. Yeah. Anytime you're you're done using radiation, they should immediately be locked in a safe place. And then eating is allowed? No, not at all. eating, drinking, smoking, never allowed because if radiation comes on the food, on the drink, on the smoke or on the cigarette and you inhale it or you swallow it um or you bite it, you just invited it straight into your body.
So, um you can't do that at all when handling radiation.
Advantages of nuclear energy, psychological bias, it's a disadvantage.
Okay, psychological bias is just people being scared. That's a disadvantage. Can be built everywhere. That's not true.
Um, you have to make sure it's uh in a very safe place with lots of um thick protective materials and a place to dump the waste. You can't just build it anywhere, especially not city limits which is so close to the city.
Does not contribute. Yeah, that's true.
It doesn't contribute. It's an advantage of UK energy.
Does not require protected material. Um, it does require requires a lot. It's actually one of the disadvantages. So, that's not true. runs on a smaller amount of fuel. That's true. That's one of the advantages.
Okay. Um what affects the rate of a radioactive decay reaction? This is like the first few questions were from LA last week's um quiz 7.4 and 7.5. So quantity and kind. Um these are the only fact things that affect the rate of a radioactive decay reaction. the quantity and the kind of material.
Okay. Um again, safety precautions. Use rubber gloves. Um not true. Um use tweezers always. Don't let it touch your hands. Never eat and drink. True. Do not look directly. True. Wash your hands thoroughly. So any radiation that was on top of your skin that your skin protected you from, wash it off immediately so it doesn't have time to enter. Store it in plastic boxes.
plastic not is not enough. Um you should use lead because lead blocks alpha and beta and prevents or like at least decreases gamaries. So um it should be stored in lead boxes.
Okay, we can use radio radioactivity to measure distance. We never said that.
Trace path of reactions and biochemical reactions. That's true. Determine the age of samples by their radioactive activity. That's true. Carbon dating radioactive dating. Sterilizing food products. That's true. Determining the brightness of stars. We never tried that or we never took that.
Okay. Advantages. Limits the production of carbon dioxide. That's one of the biggest advantages of nuclear energy.
Limits the production of acid. Again, very big advantage. No shortage of fuel.
You can just make more plutonium. So, there's never going to be a shortage of fuel if you if we um nuclear energy starts becoming widely used. cheap to build. That's not true at all. It's very expensive and no waste. It does produce waste.
Okay.
Uh radioactive source emits radiation to the space where a magnetic field is present. This source emits alpha and gamma. So there's no better at all.
Okay. There's no better particles at all. So here we when we have a magnetic field when the magnetic field is um into the picture this symbol means into the picture. This symbol means out of picture. When it's going into the picture that means alpha is going to up go up like this.
Gamma is going to be unaffected and then beta is going to go straight down like this. Okay. Um if it's this is for out of picture. If it's going into the picture into the picture like this if it's going into that means that um alpha is going to be deviated down. Gamma is always going to be undeviated and then beta is going to be deviated upwards.
Okay. So here in this case we have no beta at all.
This is gamma. We have no beta at all.
Okay. So um we can just erase that.
because it's going into the picture that means alpha is going to be deviated downwards. So A, B and C are three um uh detectors. Okay. So detector A is not going to detect detect anything because detector A is up here. Detector B is down here. Detector C is down here. So detector A is not going to detect anything because there's nothing there.
There's no beta. So it's not going to detect anything. Detector B is going to detect the gamma radiation and then detector C is going to detect the alpha particles deviating downwards.
Okay, this is electric field. So alpha particles are positively charged.
They're protons and neutrons. So they're positively charged which means they're going to be attracted towards the negative um field. Okay. So, alpha is going to be deviated downwards in this case because the electric field the electron one is the negatively charged one is down. So, alpha is going to be um deviated downwards. And then gamma part gamma um radiation it has no charge. So, it's not going to be um affected by the magnet by the electric field at all. And then um um alpha particles uh and beta particles sorry beta particles are electrons. So they are going to deviate towards the positive positively charged um electric field. So beta is going to deviate upwards in this case. So detector A is going to detect beta. B will detect gamma because gamma goes undeviated. and then C is going to detect um actually in this question they said that there was no they only emit beta and gamma there is no alpha at all so because there's no alpha there's nothing going to be deviated downwards so C is going to detect nothing okay so we had a nitrogen isotope okay um we had 15 um neutrons which means that we had nine neutrons and six protons in this case. Bottom number is protons. Um number on top is nucleons nucleons and um number on top minus number on bottom will give you the number of neutrons which is nine. And then after the reaction, after something happens, after it decayed, uh we had 15 um uh nucleons, which means 15 - 7, we had eight neutrons and we had seven protons. So what happens is we can tell by the numbers before and after one of the neutrons turned into a proton. Okay. When a neutron turns into a proton, that is um better uh that is better um decay. Beta decay is when either a neutron turns into a proton or a proton turns into a neutron.
In this case um neutron turns into a proton. When a neutron turns into a proton, it releases um a negative electron. Okay? And then when a proton turns into a neutron, it releases a positron, which is an electron with the same mass but um but different charge.
So it's a positively charged electron.
When we go from when when one of the protons turns into a neutron, it releases a posetron. But in this case, we want neutron to proton. So that means we release an electron. Okay? So in this case, um they wrote it over here. The symbol for electron, the nuclear symbol for electron or the chemical symbol for the nucleus of an electron is um zero on top because the number on top a is um for protons plus neutrons. If it's just an electron, it's got nothing up there.
So, it has no protons, no neutrons. So, up there it's always zero. And on the bottom, on the bottom is usually a symbol for protons. But in this case, we don't have any protons, but we do have an electron. Electron is a negatively charged um is negatively charged. So for electron we always symbolize um we always use in the place of Z we put negative 1. So just memorize the symbol for electron is 01. So A is 0 Z is 1.
Okay. um graph below shows activity due to um given radioactive as measured by a detector background radiation level is 25 counts. Now this in this case the detector measures background radiation level as well. So first question is asking what is the measured count rate at zero time of the source alone.
So this source uh this dete detector measures source and background radiation. Okay. So at zero time, okay, at zero time, uh the radiation or the count rate because on the y-axis they're counting the count rate, the count rate is 120 at zero time. So the detector is detecting 120 um um count counts of radiation from the radio radioactive source and the background source. The question just wants the radiation source, doesn't want the background source. They told us in the question background radiation level is 25. So that means the background level is 25 and the total is 120. To get the radiation level, all we need to do is do um 120 minus 25. That means the amount of radiation being given out by the source on its own is 95. Okay.
Now here they want us to find what the counter rate after one half life is elapsed due to the source alone. So again we're looking at the source only.
Okay, we're not looking at the background radiation just the source.
Okay, after one half life has passed one half life is just the amount of time it takes to half the amount that we had in the beginning. So what is the amount after a half life? The amount after halfife is just half the amount in the beginning. So they want the the the amount after a halfife of the radioactive source on its own. Okay. So radioactive source on its own. We divide the radioactive source only by two. We get um 95 divid by two we get 47.5.
So that means the the amount of radiation after one halfife okay of the radioactive source on its own is 47.5.
Okay. Now it wants the counter rate measured by the detector. Okay. So the amount of radiation given out by the source on its own after a half life is 47.5. Okay. Now the detector it doesn't just measure 47.5.
It measures the background rate as well.
It doesn't just measure um it doesn't just measure the radioactive source. It measures the background rate as well. So all we need to do to find the this rate over here is just add 25 cuz 25 is the background rate. So 47 + 25 is 72.5. So that means the detector measured 72.5 count rate 47.5 from the radioactive source and 25 from the background after one halfife has passed.
Now it wants to know what the halflife of the source is.
Now um to find the halflife okay we go back to the graph when we had uh now this graph measures the uh count rate measured by the detector. So the values showing up on the graphs are 120 at zero time and at after a halfife um it shows 72.5. So what's on the graph is what um is what the detector is seeing. So 120 is 72.5.
So when we go to the graph and we're trying to find um how do you find halfife anyways? You take a point okay a you first take the point at zero time.
So 0 and 120. Usually you would divide um 0 and 120. Usually you divide the um the amount at the amount you had at zero time. You you would divide it by two to get the new y and then this the new x is you subtract x - 0 and the x - 0 is going to be equal to the half life. But now in this case because this graph also has um this graph also has uh background rate. So the values showing up on the graph are 120 and 72.5 which is what the detector measures. So when we go to the graph we're going to measure um we go we're going to go to 120 after one half life has passed the what's going to show up on the graph is 72.5.
So we know that one half life has passed and we know that when one half life passes 72.5 is the amount on the detector. So when we go to the graph to see the amount of time between this and this we take 72.5 as a second value. And then we look at the second x. The second x which is the x attached to 72.5 minus 0 is going to equal the halflife. So if we go here at 120 the time was uh zero.
Okay. And then to get from 120 to the after 1 half life 120 would be 72.5. So 72.5 is between 80 and 60. Now to be able to find what each blank is equal to. Okay. we do um bigger number which is 80 minus smaller number which is 60 over number of spaces. So we count the number of spaces 1 2 3 4 5 there's five spaces.
So 860 80 - 60 20 / 5 is 4. So that means each space is four um four numbers. So 7 60 this is 64 this is 68 this is 72 okay so this is 72 this is um 76 okay so 72.5 is just a bit higher than 72 so we go like around this range right so we go down okay we get approximately between this blank and this blank now to find out how much the blank is cuz it can be different on the x axis than the y-axis.
To find out what the blank is, we do same thing. Bigger number 10 minus smaller number zero over a number of blanks which is five. 10 / 5 is 2. Which means each blank stands for two. So this is 2, this is four, this is 6, this is 8. We our line is between 6 and 8. So we are approximately at seven. So that means the halfife is 7 minutes.
And those are all the questions ask answers.
Okay. Um here they want us to find the h. Okay. So for this we use the equation which is a n= a o time um uh sorry divided by divided by two power n. A N is the final um final amount actually no for this question we don't need the equation because they give us it in percentages. Now in the beginning anytime any amount that we have in the beginning okay um whatever amount of carbon 14 we had in the beginning is 100% of its original amount cuz we didn't lose anything so we had 100% of it and then um after one half life has passed. Okay after one half life has passed I'm I'm going to write half life as HL after one half life has passed half of it was um half of the 100% was divided by two. So now we have half of the amount and we have 50% of the original amount. Then another half life passed. We had um another 50% uh another we divide 50 divide by two. So now we have 25% of the original material. And then another half life passed. 25 / 2 we have 12.5% of the original material. So it took three half lives. 1 2 3 to reach 12.5% of the original material of the original amount. So three half lives if one half life is 5,700.
Three half lives are just times the so 5,700 * t is 1,00 17,00 years. So approximately the age is this much.
Okay. um heavy nucleus splits into two lighter nuclei um upon being bombarded by neutron is fision. Okay, just memorize it.
Okay, here we we can see we we released the electron.
The only radio radioactive decay that releases electron is beta decay. And we know it's beta minus decape because we released an electron or a posetron. And because we lost a proton and um uh that proton turns into a neutron. So when a proton turns into a neutron, we released an um electron. That's called butter decay.
Okay. Here this is the cloud chamber.
Again, just memorize these pictures. I explained it in last last week's um because if you don't understand that alpha has always bold straight lines.
Beta is usually they like to present it in dotted lines to show how thin they are. So beta is usually dotted lines.
And then gamma is see how they're all small disconnected lines and they're not straight at all and they're like not coming from a source like beta and alpha. They're just um disconnected.
That's because gamma doesn't give any tracks. So, so there's not going to be like a central source in the middle showing up. So, um when it's short segments, it's gamma. So, just memorize the pictures for each one.
Okay, here these are steps. Um again, gajiller tube was in 7.4 and 7.5. So first thing that happens is radiation hits the tube and it enters and when it enters it creates it ionizes the argan gas in the tube and then those ions are attracted to the opposite charge electrons and while they're doing that they make other ions and because an electric current is just the movement of ions. So an electric current is formed and that electric current can be translated into a counter that counts each radiation particle entering or a click that clicks every time a radiation enters. It can be any noise, not just a click.
Okay, half um quantity to decay is half life.
Again, just definition to memorize.
Okay. Um whenever we're trying to find a the halflife from a graph, we take a point. Okay, here let's call it the first point ta. Okay, this first point ta usually t is better to be zero, but we take ta. Okay, and then to find the second point, the second point a has to be equal to um a1 / 2. So a1 divided by two is going to give us a2. Okay. and then a2. To find the t of a2, we just go to the graph. We find the x value of of this y. And the x value will be the second time. And okay, so to find the halflife, we do t2 minus t1. But if you pick t1 as zero, you don't even have to subtract cuz you're going to get t2.
So here they're asking um here they consider a prime as a2.
So here we can just change it.
A prime. Okay. So the A prime is equal to A or A original or A1 or A as they put it in the question. A1 / 2. So A1 / 2 is 0.5 * 2.
Now to use the graph um we just use the same steps I said now. Okay. We take a point point um try to make x0. So um take a point at the origin at zero time the amount is 80 and then 80 / 2 is 40.
So to we go to 40 on the graph 40 is here. The time at 40 is 2.
Okay. So to find the halflife we do t2 - t1 2 - 0 2 which means the half life is 2 days because it's in days. So 2 days.
Okay. Um what is an alpha particle?
Again memorize a helium nucleus. Two protons two neutrons.
The number of protons in the nucleus is um Z is the the bottom number Z is the amount of protons which is 95. And then to find the number of protons we do A minus C. So on top the number on top minus the number on the bottom we get 146. Now when we release um an alpha particle that means we release two protons so the proton number goes down by two and we released two neutrons so the neutron number goes down by two also.
Now the time it takes for 1 g of amium to decay. Um so 1 g okay after a one half life has passed one half life is 432 days. So after one half life has passed uh we divide one by two 1 / two is 1 / two. Okay then that's still not the amount we want. So after another half life has passed 1 /2 will have divided by two again which will be 1 / 4 which is the amount that we want. So it took two half lives to get to 1 over 4. 432 + 432 is equal to 864 which means it took 864 days to go from 1 g to 1 over 4 g.
A patient suffering from a disease of the thyroid gland may be asked to swallow a dose of a form of a radioactive form of iodine. The amount of this iodine absorbed by the thyroid gland can be measured using a suitable radiation detector. Now the iodine um used should be gamma. Why? Because if it was alpha it would not have been able to be detected by the detector because the detector can't enter your body. Okay? We have to put it like outside your body and detect the radiation leaving your body. Gamma would um alpha is not able to leave your body. It can be blocked by a piece of paper. Your body tissues, your muscles, um your bones are all enough to to block alpha particles. Same with beta. your fat, your muscles, your um tissues, your bones, those are all stuff that block alpha beta particles from leaving. So alpha and beta would not be able to leave your body. The only ones that would be able to leave your body and be detected by the gamma emitter is by the gamma detector is gamma radiation.
And um radioactive isotopes in this treatment should have a short halfife to make sure radioactive material decays significantly and does not stay too long. We don't want radiation inside our bodies for too long because um they can affect our cells if they stay for too long. So we have to make sure that um it decays quickly and a lot by a lot and have a very short halfife so that it doesn't stay in your in your body for a long time and damage your cells.
Okay. Um any tracks in a cloud chamber are caused by the um vaporized the alcohol vapor or the water vapor in the air being condensed by the by reacting with the ions. So any attacks in a cloud chamber are always left by condensed liquid either condensed water or condensed alkon.
And the radiation that leads to this is gamma. Why gamma is because for um they're very short segments. Okay, if you'll see, they're like this. Okay, they're very short segments and they're curled. Alpha would be in a straight line. So, we know it's obviously not alpha. Beta would be very thin. These are thick. These are like um like this thick. Okay, they're thick. And um beta would be very thin and it would be um coming from a source in the middle like this. Okay. And um these are not doing that. These are small segments coming from nowhere and they're just like in separate um amounts.
So these are most likely gamma. They can't be alpha. They're not straight.
They can't be better. They're not coming from the center and are very small segments and they're very thick.
Now um it's asking about the magnetic field in the chamber. But the thing is we can't tell what direction the magnetic field is in if it's even there or not. Because gamma does not get affected by a magnetic field. So if it was there, gamma would be the same as if it as if it wasn't there. So it's impossible to tell because this type of radiation gamma is not affected by the field.
Okay. Um to get the background rate um we just do background radiation or radiation divided by the time.
Okay. So here we have 750 counts. Those that's the amount of radiation over the time which is in minutes. Okay. Now background radiation is measured in BQ or BQ is equal to counts per second.
Okay. These are counts per minute. Okay.
So to um to go from counts per second to go from counts per minute to counts per second, you um multiply by 60 or divide by 60.
Oh no, sorry. You multiply by 60. So to go from counts per minute to counts per second, you multiply by 60. So this um 750 / 5 is 150 counts per minute. To go from 150 counts per minute to um counts per second, you just divide by 60.
So counts per minute. To counts per second, you divide by 60. 150 divide by 60 is 2.5. So that means you have 2.5 BQ. Oh, sorry. I don't multiply. I mean divide to count per minute to count per seconds divide by 60.
And then this is just a fact to memorize. Major source for background radiation. Most background radiation is radon. Okay. 55% of all background radiation is made out of radon decay. There's other um factors such as food and drink and um ground and cosmic rays and all those stuff but the main part the biggest percentage is radon.
Okay, here it's asking for isotopes of potassium. Okay. The most stable one um um an an isotope is very stable if the ratio of neutrons to protons is almost 1 one or 1:2 at least. So 1:1 means same amount. 1:2 means one is double the other. So here to get the number of the number of protons is 19. Number of neutrons is 40 minus 19 which is 21. Okay. Here 3. The number of protons is 19. It's 19 for all of them.
Protons is 39 - 19 which is 20. Here um neutrons are 36 - 19 which is 17. Here 34 - 19 15. So the one that's closest the the isotope with the closest amount of um neutrons and protons like almost equal is this one. Okay, there's only one one uh one extra neutron which means this is almost one one which means it's the most stable one and then um one of them one of the potassium isotopes. So potassium under goes beta minus decay. Beta minus means a a um neutron turns into a proton. Okay.
So when a neutron turns into a proton that means it gains an extra proton. So when it gains an extra proton it atomic number goes up by one. So when its atomic number goes up by one it go it goes from 19 to 20. though. Um, and it becomes because calcium has uh has 20 atomic number that means the element it becomes is calcium cuz now it has the same atomic number as calcium.
Okay. So to find the half life um do same steps as usual. You go to time z.
Okay. It's best to take the value at zero. The radiation value at zero is um to find the value of each of these gaps you do 4500 big number minus small number over the number of gaps there's five. So 4,500 - 4,000 divided by five is 100. So that means each gap is 100. So over here this is this point is at the second gap which means it's 4,200.
Okay. This is 4,100. This is 4,200.
So um this point is 0 4,200.
Okay. Now the second point to find the second point we divide the the second um we divide the y by 2. 4,200 / 2 is 2,100.
So to be we go to the time that has 2,100. Okay, 2,100 is around here. Okay, this is 2,00 and this is 2,100. So 2,100 the point is over here. So we go down with this point.
Okay, it stops around here. Now to find out how many blanks that is, we do the same thing.
Big number five minus small number zero over number of blanks which is 1 2 3 4 5 6 7 8 9 10. So 10 5 over 10 is um 0.5.
So each blank is 0.5 0.5 1 1.5 2 2.5. So what we're at is 2.5 seconds.
Okay, 2.5 seconds is the halfife.
And then the background radiation rate on a graph with background radiation to the part where it starts becoming horizontal. Okay, the value of the activity the activity or the value of the activity where the graph starts becoming horizontal by horizontal I mean like completely flat on the x-axis it's around the bottom where over here it starts to go flat okay it's the graph it's it's going down and then it starts to flatten out at the x- axis the value of the activity of the y value um um the y value where it starts getting flat is the background ground radiation weight.
So this line is where it starts going flat or where it becomes very flat.
Okay, it's around this much. So um over here is approximately like nine um burwell. So just look at the part of the graph that um where it starts almost becoming completely flat.
Okay. The halflife is um to find the half life same thing. Take a point.
Okay. X is zero and then y is 200.
Okay. To find the x value, to find the uh to find the second y value, divide by two. 200ide by 2 is 100. The value of the time at 100 is 1. So time 2 - time 1 1 - 0 the halfife is one.
Okay.
Um 3 years after it began. So for this one we can just use the formula a n = a initial / 2 power n is the um half life.
So 2 ^ of 1 over oh n is the amount of half lives pass. So it's to the power of three because 3 years after them is passed. So over 3 years is three half lives. So um 2 ^ 3 / a initial initially we had 200.
Okay. And then finally is x 200 / 2 ^ 3 is 25 and the unit is in mg. So 25 mg.
Okay. Here same thing formula a n = a / 2^ n um halfife is n. So it was initially 120 then it went down to 15. Okay. So they want to find the halflife.
Okay. And it's the halfife. So to find the halflife um we bring 2 n to the other side and when we bring 2 n to the other side it becomes 15 * 2n = 120 and then we can take 15 to the other side so it becomes 2 n = 120 over 15.
Okay. So 120 over 15 is um 8. So 2 ^ of n= 8.
So that means that um when when we do lin of 8 over l of 2 is lin of 8 over l of two is equal to the power which is n l of 8 over l of two is equal to um to three. So n is equal to three. Three is not the half life. Okay? Three is the number of half lives. When I when I say to the power of n, n is the number of half lives. Okay? So if that's if um if there three half lives passed, okay. And um three half lives passed. Okay. And 21 seconds. So 20 seconds to 21 seconds is three half lives.
Okay. So that means 1 halfife is 21 / 3 1 half life is 7 seconds. Okay. So half life is 7 seconds. Even in part B we accidentally see the answer. A further 7 seconds later the mass of the sample becomes we don't even need to use the equation. It was 15. Okay. Another halfife passed. That means it divided by 2. 15id by 2 7.5 because 7 is um the halfife. So after 7 seconds passed that means another halfife passed. So divided by 27.5.
Okay. Here it wants the equivalent dose.
It's not asking you for the actual value of the equivalent dose. It just wants which one has the highest, which one has the lowest and rank them. Okay. So the one with the highest equivalent dose is um let's find the equivalent dose of each one. For alpha particle the to find equivalent dose you do absorb dose which is 2 * 20. So 2 * 20 is 40. So that means that the equivalent dose is 40 for alpha particles. For beta it's 30. 30 * 1 is 30. You don't the the um weighing factor is one. So it's 30. For gamma it's same thing. It's 50. You don't multiply anything with it. X-rays as well. X-rays are also a type a type of um electromagnetic radiation and they also um they're in the same group as gamma radiation. So that means they're also times one by one. So 0.5. So that means we have 40 30 50 0.5. The highest one is gamma at 50. So that means it gets the first.
Second place is 40. Third place is 30.
And then last final place is 0.5.
Okay. Um level of yogurt in a cup is to above a certain level.
Okay. So um the type of radiation you use here if we used alpha they would get blocked by the glass cuz um sorry the reason we're using um radiation is to check the yogurt level in the cup. Okay. So if it's too low that means the detector is going to detect a lot of radiation. If it's high enough that means the radiation is going to decrease which means that the when it decreases to a certain amount that means the real is at the correct level. So if you use alpha it's going to get blocked by the container.
So it's not going to be able to pass through detector won't detect anything.
If you use gamma gamma is just going to not going to be blocked at all. Okay.
And it's because it's not going to be blocked at all. you won't be able to measure the difference. Okay, beta will be able to go um pass by. Okay, and then when the yogurt level starts to rise up, that means that the amount of beta particles will start to decrease a bit and the detector will detect less. And that's um when the detector detects less, that's how you know that the level of yogurt is at the right level. So um beta particles are the best ones to use.
gamma won't change. Alpha won't reach the detector. And it should be long because if it's short, um if it has a short halfife, that means it's going to decay and decrease before the yogurt even reaches the correct level. So um if it has a long halflife, that means it can um it can it will stay constant like the amount of radiation will stay constant for a longer time. If it if it decayed quickly, that means it would decay. Even if the if the yogurt was down here, it had a quick halfife. It would already be decaying and be showing the detector less even if the yogurt didn't bleach. So, you would think it was fully fully um it was fully uh it was at the highest level, but um it actually wasn't. It was just the radiation decaying. So, it has to have a long halfife. It can last a long time up until the yogurt reaches upwards and it's and the radiation starts to decrease which tells us that it's at the correct level. Okay, that's all.
Related Videos
Is dark matter real? - Why can't we find it? - physicist explains | Don Lincoln and Lex Fridman
LexClips
1K views•2026-05-30
Saptarshi Basu - Spectacular Voyage of Droplets: A Multiscale Journey to Extreme Flow Conditions
DAlembert-SU-CNRS
152 views•2026-06-02
A 6.0 Just Hit Hawaii — And It Came From The Wrong Place
TerraWatchHQ
115 views•2026-06-03
The Split-Second Mistake That Made Bouncing Bettys So Deadly
NoMansLandChannel
253 views•2026-06-02
Nobody Expected This Lava Reaction 🤯 #faits #facts
TendzDora
28K views•2026-05-30
The Silent Memory of Glass
UnchartedScienceworld
146 views•2026-05-30
The Difference In Charged And Neutral Particles
heavybrainspace
959 views•2026-05-29
A380 vs Every Vehicles Crash Test Challenge | Which One Win?
BeamLap
163 views•2026-05-29
