Final and Full Revision of Coordinated Sciences 0654 Physics March 2026

Hinzugefügt: 2026-05-12

[00:00:00]Hello everyone.

[00:00:03]Uh today we are going to uh solve uh March 2026 paper 42 uh coordinated uh sciences 0654.

[00:00:17]Uh I think I didn't find a lot of u content related to uh coordinated sciences online. So I think this is it will it will be a good opportunity for all students studying uh um coordinated sciences. This is the most updated available exam which is March 2026 for the coordinated sciences and I think this this will be very useful revision. So we will cover most of topics and at the end I will give very important tips and uh formulas and lot of things related to uh the exam and please I remind you guys please like the video and subscribe okay I have many students and but I don't see any subscription so please subscribe and like and leave comment okay so let it like I mean um be shared with more students to be useful for everyone. one.

[00:01:13]So question number nine, this is the first question for uh physics. Um state the boiling temperature of pure water at a standard atmospheric pressure include uh the unit. So the the boiling temperature as you know it's 100 Celsius. So don't forget to write the unit even if they didn't ask for the unit. And since they ask it for the unit, if you not read the unit, you will not get the full mark. Okay.

[00:01:47]Uh next one is about describe evaporation in terms of particles. And usually look you have two points here.

[00:01:57]So you have usually when you have a question about describing or explaining you should explain in details. Okay?

[00:02:07]Don't make like short uh notes.

[00:02:10]Okay. So when we talk about uh evaporation, so we talk about in terms of particles.

[00:02:18]So those particles at the surface of the liquid, okay, at the surface of the liquid and they have like the most energetic and the most kinetic energy comparing to other particles. Okay. So this is the first point you have to mention that particles at the surface of the liquid. Okay, it's very important to say that that it's that's add surface of the liquid. Okay.

[00:03:00]And they have what? They have like the most have most or they are the most um energetic or most second.

[00:03:24]Mhm.

[00:03:27]most energy or most kinetic energy.

[00:03:29]Let's say most kinetic energy.

[00:03:38]Okay. So this very important. So you are relating particles as they mentioned and they are on the surface and you are talking about the kinetic energy. Okay.

[00:03:48]This words are the key words you have to mention them. This is this is just number one. Okay. number two. Okay, since two points you have to make like three statements. So those um particles, okay, those particles with this enough or most kinetic energy since they have this high kinetic energy, okay, they will overcome, okay, the attractive forces uh between them and the neighboring uh particles.

[00:04:31]Okay. So because of this they could escape. So you have to mention uh the reason. Okay.

[00:04:41]So they can overcome.

[00:04:46]Okay. The attraction forces.

[00:04:50]The attraction forces.

[00:04:56]Okay. and escape.

[00:05:00]Okay. Escape from the liquid. From liquid. Mhm. Like what?

[00:05:11]Okay. So, please don't forget the key words and don't forget to talk about that they have enough kinetic energy so they can escape from the liquid. Okay? Don't just write one word and expect to get the full mark.

[00:05:29]Then explain why an increase in temperature of a liquid change the rate of evaporation.

[00:05:37]So if we talk about why increasing temperature so increasing temperature what it will increase increasing temperature will increasing the kinetic energy. So it's more motion.

[00:05:52]So it's uh now it's easier to overcome.

[00:05:55]So more particles would overcome and escape. It means increasing the rate of operation. Okay. So now let's write this. So how many points we have here?

[00:06:06]We have two. Okay.

[00:06:09]So higher temperature means Particles have more kinetic energy. Okay. More kinetic energy.

[00:06:39]Okay. And this will lead to what? And this one will lead that. So this is the second statement. So more particles can escape right?

[00:06:51]More particles they will escape from the surface. Okay.

[00:07:00]And the surface okay will escape.

[00:07:10]Okay.

[00:07:12]And this will lead to what?

[00:07:15]And means and that means increasing in the evaporation rate. Increasing the rate of evaporation.

[00:07:40]Okay guys, so this is the two statement. So usually try to not just to say oh particles move faster. No, you need to connect this one uh more about the ability to escape.

[00:07:56]Okay, they they get kinetic energy. Yes.

[00:07:58]So this will since they have more kinetic energy, it means they will overcome they have more they will overcome the the attraction forces. So they will escape and then they will increase the rate of operation not just they will be faster.

[00:08:15]Okay.

[00:08:16]So next one complete the sentences using the words from the list. So now look thermal energy transfer takes place by space in all solids. In solids as you know it's conduction and liquids and gases. Okay, liquid and gases what we call it fluid. So if you see this one and this one it's the same thing fluid like liquids and gases.

[00:08:50]Okay, this one is convection.

[00:08:57]Okay, vacuum. When you see vacuum you remember what you remember the sunlight comes okay from the sun okay through space to us. So remember this one. So it means what? Radiation.

[00:09:13]Okay.

[00:09:16]Next one. This one is just as you see it's just um I mean to complete the sentence. By the way, take care about this questions when you have uh this type of questions because in exam you will not be uh graded by 0.5 or 1.5. So in this exam in this question you will get one or two.

[00:09:41]So losing one of them it means you will get one out of two. So please get the full mark. Okay.

[00:09:51]Next question. Still we are in thermal physics.

[00:09:57]Mhm.

[00:10:00]Now, uh the figure 9.1 shows an ice cube submerged in water and held in place with a plastic goose. The boiling tube is heated halfway along its length with Bunson burner flame. Okay, if you look at this one before knowing the question, look how it looks like. Look, the ice is here.

[00:10:25]while it's heating here on the top.

[00:10:29]Okay, so this is before looking at the question to see how it looks like. Okay, so explain why the ice cube doesn't melt rapid rapidly when the water at the top of the boiling uh tube is boiling. So here it stop is boiling.

[00:10:48]Why the ice okay doesn't melt rapidly.

[00:10:55]So number one or let's look at the question. How many points we have?

[00:10:59]Three. So don't just write one word. So let's start with with this one. This one here is water inside. Number one. The water is poor conductor of heat.

[00:11:16]Okay, because to transfer heat from here to there through water, it's poor conductor.

[00:11:29]This is number one. Okay. So, it's not easy, okay, to travel downward by conduction. Okay, by conduction it's not easy as you think. So look, we said poor conductor and what I'm going to say I'm going to say conduction. So you have to mention usually conduction, convection and and those keywords. Okay. So heat doesn't easily travel. Okay.

[00:12:09]by conduction.

[00:12:14]Mhm.

[00:12:17]Next point.

[00:12:19]As you see that the top part the top part is is uh the hot water at the top. And this is actually a problem for us. Why? because it's uh usually when it's hot it will be less dense and it goes up and already it's up there it will not go down okay so the hot water goes up it will not go down to the ice okay because less dense goes up okay this is the second problem we have okay so hot water at the top. You know, if if it's re if if if we were hitting if it was different and and we are hitting uh down downward like the bottom it could be different but we are heating on the top.

[00:13:18]So hot water at the top and of course it's less dense.

[00:13:26]Okay.

[00:13:28]And uh so hot water is less than than the cold water, right?

[00:13:38]Mhm. So this hot water will stay because it goes up, it will stay there at the top. Okay.

[00:13:52]Now uh since it stays up there so it doesn't go you know if if it's if there is if it goes down and goes up and down so we will have this current okay we will have what we call it this current we call it what convection but we have no convection okay so also okay it doesn't uh the current doesn't go down Okay.

[00:14:25]So, no conviction downward.

[00:14:35]Okay.

[00:14:38]So, what does it mean? What is the conclusion here? The conclusion here that less thermal energy will reach to the ice. Therefore, less thermal energy.

[00:14:58]Okay.

[00:15:02]Reaches to dice.

[00:15:07]Okay. Or riches dice.

[00:15:11]Okay.

[00:15:16]So please guys again try to explain very well your answer like because this is three three marks. Okay, you have to explain why uh using this both conduction or convection. Okay, this this uh this will not help that one. So you have to say that water is poor conductor convection hot water is is less dense. So it stays at the top. So and no downward conviction and so on to get the three marks. I'm not asking you to write 1 2 3. I'm just trying to explain to you that you have to explain like at least three statements.

[00:16:02]Next question.

[00:16:04]Now describe a transverse wave.

[00:16:10]So um the transverse waves guys it's when the wave Mhm.

[00:16:20]uh moves in like uh in which the the vibrations or we call it oscillations of of particles they are moving perpendicular or at right angle to the direction of wave travel or direction of energy transfer.

[00:16:41]Okay. So if we have we say like something like that and the wave this is wave travel in this direction and the particles themselves it goes like up and down up and down like perpendicular to to the direction of wave travel or direction of motion direction of energy transfer.

[00:17:06]So a wave in which the vibrations okay or oscillations write any of them of particles is right angle or at at 90° or perpendicular.

[00:17:40]Okay, don't say in exam just transverse means uh the wave is perpendicular. You will not get two points.

[00:17:51]So you have to say what exactly is perpendicular and perpendicular to what?

[00:17:58]Okay. So the oscillations or vibrations they are perpendicular of of particles they are perpendicular to the direction of like energy transfer.

[00:18:16]You can say energy transfer.

[00:18:21]Okay. Or you may say the direction of wave travel.

[00:18:27]Okay. Mhm. Again key words to say vibrations and they are perpendicular on the direction of okay of energy transfer.

[00:18:41]Now they said uh set an example one example for of transverse wave.

[00:18:50]Look all the electromagnetic spectrum they are transverse all them. So you can say light or visible light it's fine. You can say uh x-ray, gamma ray, uh radio waves, microwaves, any of them. Okay.

[00:19:10]Or even you can say water waves also.

[00:19:15]Water waves they are Mhm. Water waves.

[00:19:21]Okay. They are transverse.

[00:19:25]Take care to write only one. If you are sure about one, write one. Cuz if you write two and one of them correct, one of them incorrect, you will not get one point in exam like the examiner will not pick for you your answer. Which one is correct? Okay.

[00:19:45]You can say that um that all all just remember this like all waves are transverse except okay which one sound take sound.

[00:20:07]Okay. And what else?

[00:20:11]and the sysmic okay uh primary okay of the earthquake waves okay earthquake waves the primary type okay this one also is um logitinal waves okay remember this because this is uh you may have an exam okay so seismic uh P or sound both of them are longitudinal waves.

[00:20:50]Okay. But anything else is um transverse. Okay guys, long okay next one.

[00:21:15]Okay, I will erase it here from the file to not I'm afraid that someone will see the file will think that this is example of transverse. So I will remove it.

[00:21:27]Okay, next one.

[00:21:32]Sound wave under goes defraction when passing through a narrow gap. Okay, so describe defraction.

[00:21:46]So this is one point.

[00:21:49]So defraction is what? The spreading out of waves. Okay. When they pass through the narrow gap. Okay. So, don't forget to write spreading out.

[00:22:04]So, caption the spreading out.

[00:22:12]The spreading out of waves.

[00:22:16]Okay.

[00:22:18]when they pass through Mhm.

[00:22:31]a narrow gap. Okay.

[00:22:35]Now the width of the narrow gap is decreased. describe the effect on the defraction of the sound wave. Okay.

[00:22:50]So here you you just to to make it like easy for yourself if the the gap will be decreased. Okay.

[00:23:02]If we have narrow gap, this will lead to what? Lead to more defraction.

[00:23:16]Actually, it's better to to draw this.

[00:23:19]So, you may be asked to to sketch both.

[00:23:23]Okay. So if you can sketch this one like uh like check yourself that you know how how to sketch them. Okay.

[00:23:33]Because this will help you uh to um in in other type of questions. Okay.

[00:23:41]When they they ask you to uh to differentiate between the two types uh if you have like narrow gap or wide gap.

[00:23:50]Okay. For example, it can be like that.

[00:23:53]Like you can make like something like this. Of course, it will be to make it uh better than this. So, if it's if you have uh let's make one wide.

[00:24:09]Mhm.

[00:24:11]So, if you have one Okay, let's try to make it this way.

[00:24:21]So if you have wide let's say like this one and you have waves in this way. So in this case you have small defraction.

[00:24:31]So it will be something like this.

[00:24:35]Mhm.

[00:24:40]Like that it's small. Okay. So this one wide gap.

[00:24:47]So it will be small defraction.

[00:24:53]But what if it's narrow? Let's make one.

[00:25:02]Mhm.

[00:25:05]What will happen in this case? You will find the defraction will be more and more. Okay. So narrow gap this will lead to a large defraction.

[00:25:26]Okay guys, so try to make it in this way.

[00:25:33]It's important usually to know how to draw. Okay. So narrow gap it means more uh defraction.

[00:25:42]Okay. And of course if you have wide gap it means less diffraction.

[00:25:53]Okay.

[00:25:57]And since we are talking about transverse so doesn't mean that you you will not um you will not study the longitudinal waves also you have to know them okay and you have to know uh how to sketch them let's have a space if you have any space I will make it here like if you you be asked it to draw you have to we can make it in this way like they are very close to each other we call it compression and then they are wide then you have again okay so in this case when they are very close to each other we call it compression okay compression compressed when they are far from each other we call it rear fraction so you should know how to to draw them Okay.

[00:26:57]The distance from uh compression to compression we call it wavelength lambda wave length.

[00:27:08]So, so when you describe the longitudinal waves, you should show that those particles are are or vibrations. Okay. The vibrations of particles are parallel to the direction of wave travel.

[00:27:26]Okay. In transfer in transverse it was uh um perpendicular but here it's parallel.

[00:27:34]In here in logitinal it's uh compressions contains compressions and refractions but in um in transfers it will be uh crest.

[00:27:49]Mhm. This one the maximum point or the peak we call it crest and the minimum point we call it to off.

[00:28:00]Okay. So please don't uh forget this details and the diagrams.

[00:28:08]Okay.

[00:28:10]Again when I revise a point with you, it doesn't mean that you you revise only the the question what I'm solving. Maybe you will have uh the other side of the question. Okay. Like this question for example, it's talking about uh find the refractive uh refractive index refractive index n= to sin i over sin r.

[00:28:33]We will use this one. Why I'm going to use this one? Because I have here the incident angle. I have I = to 60°. And we have r the refraction angle. It's written here uh r = to 41°.

[00:28:50]So I'm going to use this one. But it doesn't mean that you should not know the other formula for the same refractive index because you the question can be changed.

[00:29:02]The other formula that the speed of light in vacuum divided by the speed of light okay in the other medium. Okay, for example, if if you are talking here about water, let's say, so in water, speed of light in water, let's say.

[00:29:30]Okay, so you should know this one because you may be asked it the to use this formula. How can I know that I will use this formula?

[00:29:41]Depends on the given data. They may ask you in the in the question. Uh they will not give you uh those degrees and they will ask you to find uh let's say uh to find n if it's given they will give you the speed of light in in in in uh the medium in water. Okay.

[00:30:03]And again you should know that it will not be given the speed of light 3 * 10 ^ of 8 m/s.

[00:30:12]So this one you should know and if they give you the speed of light in motor in this case you will divide them and you will get n. But in our question here is easy thing we have sin I I is 60 divided by sin r and r here is 41.

[00:30:32]This will give you 1.32.

[00:30:36]So this is the answer.

[00:30:39]A very important note here number one that uh when you sin 60 over sin 41 please double check that your uh calculator the mode is degrees because this is 60° 41° not radian. Okay.

[00:31:00]Uh number two some of you they forget and they write sin 60 / 41 without sign.

[00:31:08]That's incorrect. Please remember that's not 60 over 41. It's a sin 60 over sin 41. Okay.

[00:31:18]And of course we cannot cancel sign of sign. Okay.

[00:31:22]Uh your answers 1.32 is fine. You can just write it there.

[00:31:29]Okay.

[00:31:33]Next question.

[00:31:37]A light ray travels in water and uh and is incident on a boundary with air.

[00:31:45]Complete figure 10.1. You have to read the question very well. They need to show what show how total internal reflection. We're talking about one case here about total internal reflection. We are not talking about refraction.

[00:31:58]So you have to draw the total internal reflection.

[00:32:02]And here they saying label you have to label what the relevant angles like incident angle like uh reflected angle both of them the angle of incidence and the angle of refraction you have to show to label them on the graph to get the three points. So use your your ruler please. Okay.

[00:32:26]So we will make dashed line that it must be dashed line for the normal and right I make here right angled and write that this one is normal. Now you will get one point.

[00:32:40]Then to have total internal reflection the ray travels in water. So it comes from water. Here again use ruler please.

[00:32:52]You have to label the incident angle.

[00:32:54]This is the incident ray.

[00:33:02]Okay.

[00:33:04]So this is the incident angle again. The incident angle usually from the normal to the incident ray.

[00:33:12]It's not this one. Take care about this because you may have a question to find the index and they give you graph the refractive index and they give you this one. This one let's say this one is uh 30.

[00:33:26]So it doesn't mean the incident angle is 30. It mean the in incident angle here let's say okay this one is 60 for example. Okay. So take care that it's here.

[00:33:41]So the question you need to label them.

[00:33:42]So you must write that here is I.

[00:33:48]Okay.

[00:33:50]Good.

[00:33:52]uh where is the uh the internal total internal reflection will happen here because it's internal. Okay, take care when you make when you draw the the ray of reflection it has to be R you first of all you will label R again it's from the normal and try to make to make it symmetrical to make like I equals to R it doesn't have to be accurate but don't make it like this it's very appears that they are not equal and that's incorrect Okay.

[00:34:33]Uh what else I wanted to remind you?

[00:34:35]Total internal reflection. You should remind yourself when it happens. This total internal reflection happens under two conditions. You should know them.

[00:34:43]Number one, when this eye, the incident angle is greater than the critical angle. This is number one. And number two, the ray must come from the more uh the denser or more dense medium to less dense. So from more dense to less dense.

[00:35:13]Those are like the two conditions to have total internal reflection. So you have to revise that. Okay.

[00:35:37]Now next part.

[00:35:46]A lamp has a current of 1.2 amps. Calculate the charge which follows through the lamp in 1 minute. State the unit.

[00:35:59]So we will learn a lot from this simple question number one that please when you write you must write the formula.

[00:36:10]Okay. At least if you if your answer is incorrect you will get the method mark.

[00:36:16]And please before writing the formula make a triangle.

[00:36:22]Okay. So what which one I have which formula I have is a relationship between the three between time I and Q. Which one is I equals to Q / T?

[00:36:43]Why I'm asking you to write the the triangle to decrease error? Because some students they they write for example that Q equals to I over T. Okay. But if you have a triangle you know that what I need to find I need to find they said calculate Q the charge. Okay. If I need to find Q I need to multiply this two.

[00:37:05]So I * T. Okay. So please draw the triangle.

[00:37:10]Okay. triangle you have the formula now please step number two substitute in the formula so Q = I I is 1.2 two ampairs.

[00:37:23]Okay. How about the time? This is the second thing to take care about.

[00:37:27]Usually, please uh convert all everything you have, okay, to the SI units, the international system of units. Okay? So, if you have minutes, make it seconds. If you have hours, make it seconds. If you have days, make it seconds. Okay?

[00:37:48]the same if you have grams make it kilograms. If you have uh kilometers, make it meters. Okay? Unless if they ask you for something different. Okay? So don't write one, it will be incorrect. I write what? All right. 60 seconds. 1 minute equals to 60 seconds. Okay. So the answer is 72.

[00:38:11]Okay. The last step. Oh, 72 only. No, you have to write the unit. The unit is columns C. So charge 72 and unit you can write C is fine or columns.

[00:38:26]Mhm.

[00:38:30]Next one. Okay. So don't forget the formula. Triangle formula substitution formula. Write the final answer and don't forget the unit. Even if they don't ask for the unit, please write the unit.

[00:38:46]Now next question. They are asking to describe the nature of the direct current DC and the alternating current AC.

[00:38:57]So what we have to do is that the DC current from its name direct current direct current it means like one direction. Okay. So direct current it means current flows in one direction.

[00:39:23]Okay. One direction only.

[00:39:30]Okay. No change. Okay. No change in direction. No direction it change. Okay. Now you get one point AC. And the second point the alternating current here they said the direct current alternating current if the question just uh DC and AC without the the direct current electric current you have to write it you have to write the DC is the direct current okay where current flows okay uh alternating current so you have to write here it's since it's written I'm going I'm not going to write it again okay so what's happening here to AC alternating so the current here is reverses the direction or changing the direction. Okay. So this one if I'm going to draw this direct current I'm going to represent it in this way and also it's good to know how to sketch it.

[00:40:27]Please sketch it like it will be like this. Okay. So if you have current let's say that this is ampere in amps.

[00:40:39]Okay. So it goes direct but AC AC is sine wave remember like sine wave goes up then change the direction down and so on. Okay.

[00:40:54]So this one is DC and the other one is AC. Okay.

[00:41:01]So this one current okay reverse or change direction reverses direction.

[00:41:16]Okay let's say changing direction.

[00:41:26]Okay. And this direction by the way it's changing as at a certain frequency certain frequency.

[00:41:34]For example, the the main electricity what you have at home it's AC and it's 50 Hz. At home you have 50 Hz. By the way, don't forget that the unit frequency it's hertz HZ.

[00:41:49]So 50 Hz uh this is AC current what you have at home. So 50 Hz, what does it mean? you have 50 complete cycles, 50 complete periods in a second.

[00:42:02]Okay.

[00:42:04]So this is example of uh the if they ask you to to say example of the AC current.

[00:42:10]This is the main current what you have at home 50 Hz. Okay. And the DC DC we get the DC usually from batteries. Okay.

[00:42:20]Example.

[00:42:22]Mhm. battery here if you give example here is main. Mhm.

[00:42:33]Electricity at home.

[00:42:42]Okay.

[00:42:44]Now, next question. We have an electric cath with a metal casing.

[00:42:51]Okay. and explain why the metal casing must be earthered.

[00:42:57]Okay, so look at the graph first. We have metal casing.

[00:43:03]We have mains cord.

[00:43:07]Okay. Mains Yeah. means electricity.

[00:43:11]Mains electricity.

[00:43:13]Okay.

[00:43:14]Uh mains cord.

[00:43:19]And we have here look plug with fuse.

[00:43:22]Why I'm saying to look at them? Because you have to talk about it. You you have to talk about this one. You have to talk about this fuse. Okay. Okay. Mr. um I don't know earththing. What's earththing or what's grounding? So earththing we connect the idea of earthing that we have like since we h we have actually like three lines one life and one we call it neutral and the other one this is earth okay so okay why we know life neutral how about earth this third one okay if you look at uh any socket at home you will find that you have third one there or sometimes it's uh you have three like that. Okay.

[00:44:16]So the third one the earth it's like when you have if this metal this uh the metal casing uh has an electricity due to any fault and if this happens so if you touch the metal casing this will give you like electric shock and this may kill someone actually. So in this case what we do is if if this live uh wire for any fault for any reason touches this uh metal casing and this may lead to electric shock for for any human because of this we use the earthing. So earthing it's like wire with like very small resistance very small resistance and mostly this wire the it's from copper because copper is very good conductor like very small resistance there. So electricity uh instead of uh moving to your body if you touch the metal casing it will go to the easiest path with less resistance which is the earth. So it will go to the earth and all this c all of the sockets on your house they are on the whole building connecting to one metal uh road uh under the ground. Okay. So any if you have any problem with electricity all of them should go to the ground. Okay. So what will happen then if I have like very high current goes to the earth I protect myself number one and then when it goes to if there is a fuse here in the plug in the plug that one the fuse will will detect high current so it will be burned. So this will uh break down or or disconnect the electricity. So this is like safety um thing for for for us. So let's write this. Let's write this.

[00:46:28]So we can say that if a fault three points okay if a fault happened and the life wire okay touches the metal the metal casing. Okay. That one metal casing. Huh? We use what the the the vocabulary mentioned. Okay. The metal casing.

[00:47:08]Okay. So it it means now what will happen? The metal casing itself will be what?

[00:47:14]The metal casing will have like high high voltage will become like with with uh become electric. Okay. The metal casing becomes live. Okay, it will be instead of live.

[00:47:32]Okay, instead of this live um wire.

[00:47:37]Okay, then without what will happen? Okay. So if we have no earthing without earththing.

[00:48:00]Okay.

[00:48:02]Anyone uh touching the casing casing the metal casing okay would receive electric shock.

[00:48:25]Okay. So this is the two points. Okay. I need to write more. The third point, this earthing wire has a low very low resistance. Okay. So the earth wire has a low resistance.

[00:48:51]Okay. And uh and this uh so the current will flow through this one.

[00:49:00]So current flow okay to earth easily. Okay.

[00:49:15]What else I can say that uh this will lead that very high current okay will go to this uh live wire. So this will lead to what that it goes to this fuse. Okay.

[00:49:29]And the fuse is is also you have to know what it why we use fuse. We use fuse to uh as a protection uh device. It's protection from what?

[00:49:41]From high current. When it detect high current. So the the small very thin wire inside will be burned. So it will open the circuit. Okay. To to save other appliances and other circuit components.

[00:49:56]So you should know what is the use of fuse and this is what's happening here.

[00:50:00]Okay. So this large current current um blows.

[00:50:11]Okay. Or burns the fuse and disconnecting the circuit. Disconnecting Okay, the circuit. Okay, I try to to explain in details. Okay, to know exactly what to write. So, please in exam write details as more as you can. Okay.

[00:50:41]Now, next question is about uh a wire carrying a current out of the page. Out of the page. So in this case um like you will use right hand rule. Okay.

[00:50:56]So please uh now imagine that you are using your handwrite rule and you are holding wire. So the thumb goes up right like out of the screen.

[00:51:09]In this case the your four fingers is like anticlockwise.

[00:51:14]Okay. So the pattern here of magnetic field it should be something like this but anticlockwise the most important direction don't forget the direction and here it will be the same try to make it uniform to make it good circles but take care when you go far try to be also far a little bit okay because the strength of this magnetic field it should be weaker when you go farther from the um from the center of the the wire. Okay.

[00:51:49]So, just make it.

[00:51:53]Okay. So, this one let's say it will make it far a little bit. Okay. Try to of course to make it better than this but don't forget the direction.

[00:52:01]Okay.

[00:52:03]Um next one. So, this one is what? Okay.

[00:52:10]Hm. Right hand rule.

[00:52:18]Okay.

[00:52:20]Next one.

[00:52:26]Figure 11.3 shows a current carrying copper rod placed in a magnetic field.

[00:52:32]So state the direction of the force on the copper rod. Look um here we uh we are talking about left hand rule. So at at the be there when we have current current only one thing and we need to find the direction of the second thing we know the direction of current and we need to find the direction of magnetic field we use the right hand rule. But when you have two like if you have the current there you know the uh direction of current and direction of magnetic field okay you have two now and you need to find the third one the force or any one of them okay so in this case we will use left hand rule okay left hand rule or filming we call it filming left hand rule Okay.

[00:53:31]So the direction of current it goes from positive to negative.

[00:53:38]Okay take care direction of of current from positive to negative. But if we talk about direction of electron it's from negative to positive electron from negative. Okay. But here we are talking about direction of current. So this is the direction of current. So here this is the direction of current.

[00:53:58]Okay.

[00:54:00]How about the direction of magnetic field? Usually the direction of magnetic field is from north.

[00:54:05]Okay. From north to south.

[00:54:09]From north to south.

[00:54:11]So now since we uh we know that the left hand rule remember that the first uh finger was for the magnetic field and the second finger was for what? For current. Okay. And so in this case the thumb will be for what? For the direction of force or motion. Okay. So if you apply this rule you'll discover that it's in this direction.

[00:54:41]So this cover road will go in this direction. This direction like uh out of the page. Okay. You can say so you can write that. So this is force direction you can write it like that. Okay. Force direction.

[00:55:03]And here you can say um out of page.

[00:55:12]Okay.

[00:55:18]Okay. To you. To you. Okay.

[00:55:25]Next one. I think this is the last question. Complete the sentence about energy resources. The sun is the main source of energy for all our energy resources. So please try to revise them and you should know what's renewable energy, nonrenewable energy. So you should know that very well and the advantage and disadvantage. Please revive them as well. Okay. So all of the main source of this is the sun except nuclear and two more. Which one? So geothermal.

[00:55:58]Geothermal.

[00:56:02]Okay. And what else? The tidal energy.

[00:56:07]Okay. So, the three you should uh know them very well. Very well. Okay guys, because of course you know that the uh resources comes from the sun. Like for example, wind comes from the sun.

[00:56:25]Why? Because sun heats the air and you know the density. So here became hot and goes uh uh goes uh up because you know when it's hot less dense and goes up and this convection so moving of the wind this is because of the sun solar of course from the sun. Um hydroelectric it's also the sun evaporates water. So you know this water cycle and all of this story. uh even um fossil fuels it's also the same because it's um like very old plants and also that uh use sunlight. Okay. So which one you will not find? Geothermal because it's this heat comes from the earth inside the earth. Okay. and tidle tidle it's uh it's because of the gravitational uh force or pull of the gravitation like uh force from the moon. Okay. So this three remember that they are not the main source of uh the sun is not the main source of of those three types of energy. Okay.

[00:57:36]and uh nuclear fusion occurs in the sun.

[00:57:41]Describe the process describe the process of nuclear fusion.

[00:57:47]Uh don't please in exam um confuse yourself about fusion and fish. Fusion came from fuse. Fuse it means join or combine.

[00:58:01]Okay. And this happens when uh when two small uh light nuclei they are combining or fusing or joining to form a larger nucleus. Okay. And this of course will release large amount of energy. Okay. So you can write that that it's um when two small Okay.

[00:58:32]light uh combine let's say fuse combine or fuse okay together two form a larger nucleus. Okay.

[00:59:10]And uh ah don't forget that releasing what?

[00:59:15]Releasing okay energy. Okay. Actually it's like large amount of energy.

[00:59:31]So what is the other one? The other one is fishing. Okay, that one it was like f i s o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o i n. This one is to uh fish it's to splat large niclas to two uh smaller one also it's releasing energy. Okay, so what's inside the the sun? It's uh nuclear fusion. Okay, like hydrogen hydrogen and they are combining to make helium. Okay, you have to know both of them.

[01:00:09]Give two uh of the statement from the big bang theory. Okay, now uh we have a question about um the space physics.

[01:00:19]Okay, this also important. Please revive the space physics. um to know also how to find the orbital speed. Okay, you should know that and um try to revise please in in general the topic because it's also you will find one question about it. Not a lot of questions here about specificics but it's important to at the end I will say some instructions.

[01:00:47]Please be patient.

[01:00:51]Okay. So let's uh write about the big bang theory. We need to write only two.

[01:00:58]So number one that the universe is be uh began from a very small hot dense point.

[01:01:04]Okay. And has and and then has expanded or expanding ever since. And the also what else that about that the universe is approximately 13.8 8 billion years old. Okay.

[01:01:24]Uh how we know that they are uh expanding? This is uh because of something uh called red shift of light.

[01:01:33]Okay. Red shift. So if you write just two are fine. So the universe began from a very small hot dense point.

[01:01:58]Okay.

[01:02:00]And expanding.

[01:02:07]Okay.

[01:02:10]Ever since what else you can talk about the the universe because this also one of the uh one of the most popular questions about the universe age. So the universe is approximately 13.8. 8 billion years old. Okay.

[01:02:47]If you wanted to talk about that galaxies are moving away from each other, it's about expanding. You may write this as well. Okay. And this uh shown by the red shift.

[01:03:00]I think this is the last question.

[01:03:03]Okay, last question here. The uh moment of a force. By the way, you should know the definition of moment.

[01:03:13]Moment is the turning force. Okay, the turning force acting on an object.

[01:03:23]Okay, the turning force, the definition of turning force also we can say the product of the force.

[01:03:29]Okay. And the perpendicular distance from the people. So this can be uh a question to define the moment.

[01:03:38]Here we have uniform beam. This is very important. When you see this uniform when when it's uniform beam it means that the center center of mass will be in the middle. So if this one one m like like 100 cm. So let's say that if we assume that this is the center approximately this one is 50 cm. Okay. So this one is Mhm.

[01:04:12]the weight of the beam. Okay. Has a weight of now we have the weight. The weight is 5.2 Ntons.

[01:04:22]So this very important so you can know the distance. Okay. Uh the beam is uh pivoted about at one end. Take care here the pivot. It's very important to know that because usually the turning force at the pivot. So the distance from the force to the pivot to here. This is to here usually. So if we talk about this one, we talk about this distance. Okay. If we talk about this one, we talk also about this distance. distance from the force to the pivot.

[01:04:56]Okay, a spring with uh with a spring constant of 27 Newton per meters attach it to the beam. They give us here uh the spring constant. Okay, 20 look it's 27 Newton per meter and since this one is 1 m so the force here is 27 Newton.

[01:05:18]Okay, it's 27 per meter. If this one uh was 2 m. Okay. So it means you multiply by 2. So this is 1 m. So 27 newton.

[01:05:30]So now we know the force of this one.

[01:05:32]That's very important. Okay. And they give me that the distance here 0.4. You can see this on the graph. Now what is the question? The beam is horizontal.

[01:05:40]Use the principle of moments. Okay. You you have to know the principle of moments to calculate the extension of a spring. By the way, um before uh talking about this, you should know like also the principle of moments that the the anticlockwise moments equals to the the clockwise moments. Okay? Or in different words, the sum of the anticlockwise moment and the clockwise moments equals to zero. Or this is the equilibrium. Okay? or the balance.

[01:06:18]Okay.

[01:06:20]So now let's find uh the answer of of this one. Okay. The if it's balanced it means like the anticlockwise moments and clockwise moment. So what forces we have here? We have uh the weight. Okay.

[01:06:39]And the weight is is goes in this direction.

[01:06:44]Okay. like uh uh clockwise uh we have this way it's 5.2 two it's a clockwise okay it goes I mean like this like it's clockwise okay so this one 52 it's like clockwise moment times what time the the distance the distance is from this force okay to this one is 50 cm okay the second One is also the other side the force in the other side of a spring.

[01:07:29]Okay. Times uh 0 uh 4. Okay. The distance.

[01:07:38]Yeah. By the way, uh okay. No, wait, wait, wait. I think let's just sinceh I I yeah I got confused here. No, this one it's still this is the K only K is 27 Newton per meters. Okay, because this one is not related to um to the length of this. It's related to to the extension. Okay, to this one. So just leave let's leave it K as it is.

[01:08:13]Okay, we need to find it. Actually we will use this one later. Okay, sorry for that. But this is the good thing about physics. You will discover by time that if there is a mistake.

[01:08:25]Okay. So we need to find they said find calculate the extension. Okay. So let's first find the force of spring.

[01:08:34]So uh by the way um usually I say convert to to uh me centimeters. I made it here 50. Okay. So uh take care.

[01:08:49]Mhm.

[01:08:52]So this one in meters. So make this one also in meters. Okay. If this one cimeters this one centimeters it's balanced. It will not be a problem actually but let's follow this and make both of them in in meters to not have any any problem calculations. So we can say now that f equals to 5.2 * 0.5 divided by this one right 0.4.

[01:09:22]So let's calculate this 0 5.2 * 0.5.

[01:09:36]So it's 2.6 divided by 0.4. So the answer here is 6.5 newtons. So this one is only the this is the force. But they asking us to find the extension. Remember again the triangle that F = K * X. So if you want to find X, the extension should be what?

[01:10:01]F / K. And since we have F6.5 Newtons divided by K, which is 27 Newton per meters. So X now will be look if you cancel N with N it will be in meters. Okay, answer will be in meters.

[01:10:21]Even if this one not given, you know it will be in meters. So let's see 6.5 divided by 27. So the answer should be 0.24 uh or 0.241.

[01:10:36]Two significant figures are okay. In physics, two significant figures are okay. In math, three significant figures, but in math, two are fine.

[01:10:44]Okay, so the answer is uh 0.24. 24 uh m. Okay. So, we are done with this exam. Uh hopefully it was uh useful for you.

[01:10:58]But okay, I will I will say some some tips and some stuff formulas I will write them again.

[01:11:08]Okay, here I wrote this notes. So, number one, please revise electric circuits and formulas. Revise transformer and the equation of transformers because you may have a uh problem about electric circuit and transformer to find the power to find the voltage current to find the total resistance or the equivalent resistance if they are parallel or series.

[01:11:30]uh transformer to find the voltage with fun number of turns radioactivity please also revise the halflife uh orbital speed the formula revise the formula so um I will now write with you the formulas again and let's see just for a final revision for you okay let's start with the first one the First one speed the speed you know it's distance over time so it's meters distance in meters and time in seconds so meters/ second this is the unit don't forget okay and then uh next one is acceleration acceleration is like the change in velocity divided by time okay so velocity it means m/s and time is second. So it's m/s squared.

[01:12:33]Don't forget the unit. Okay. Uh this also will lead us to what please? The uh speed time graph. Speed time graph.

[01:12:48]You should know the speed time graph and how to find the acceleration.

[01:12:52]Okay. The rise over run and how to find the distance. Distance is what area under graph?

[01:13:04]Okay.

[01:13:05]Then if you want to find the weight, the weight is m * g and the weight the unit is in Newton. And as you know like uh m is um it's the same as the Newton second law like f equals to m * a. Also it's in Newton. Newton itself it's equivalent to what? Kilograms and and as you know the acceleration is m/s.

[01:13:36]So Newton is equivalent to kilog m/s squared. Don't forget this one. G in exam make it 9.8 m/s squared. 9.8.

[01:13:49]Okay. Don't make it 10 uh to be to have accurate answer. 9.8 or 9.8. 281.

[01:13:57]So uh for density, yeah, don't forget density d or row equals to the mass over volume. So if mass in kilogram and volume is in cubic m. So the unit is kilogram uh and per cubic m.

[01:14:20]Okay. So this will lead us you have to know how to find the volume of tanking if it's a cuboid for example you multiply the three sides okay uh what else um moment we found the moment right so the moment we said it's the force times the perpendicular distance take care it's perpendicular uh distance from from where from the force to the pivot from the force to the P. So the unit here since this one in meters and this one uh newton and meters so newton meter okay then the work the unit of work guys let's make it capital W so the work is force time what time distance so the unit also newton m but the work unit we use jewel Okay. Or jewels.

[01:15:25]The unit of work, it's the same unit of what? Of energy.

[01:15:32]Okay. Because the energy what you have, you will consume to do the work. They are equal. Okay.

[01:15:40]So, do we have more space? I think we have no more space. Uh, what else? Yes, you have to know the the formula for kinetic energy is 12 mv².

[01:15:53]You know m is u mass and v is the velocity and kinetic energy again in jewels. Uh potential energy or gravitational potential energy it's mg h m is mass g the gravitational force and h is the height. Okay. Also in jewels they are in most of examples you will have they are equal equal all the kinetic energy will be trans all the potential energy will be transferred to kinetic energy.

[01:16:24]What else the power the power is the work over time or energy over time because work equals to energy. This is also important to know why because when they ask if you ask you to find the energy you will say that it's the power times time. So you may say that the power later you will know that power is what is VI.

[01:16:55]The power is VI. The voltage V is voltage or potential difference.

[01:17:01]Okay. Potential difference.

[01:17:04]Okay.

[01:17:06]So E equals to V it.

[01:17:09]Okay.

[01:17:11]And we know before that Q equals to what? Equals to R uh sorry um I I equals to Q / T. So from this one you know that Q = to I * T. This what we did this exam. So you can remove this substitute it T by what? By Q. So E is V * Q. And this leads to what leads that V is E over Q.

[01:17:44]Okay. What does it mean? Uh V equals to E over Q.

[01:17:49]It means that the voltage or the potential difference is the amount of energy per each uh charge like if you want to give a definition for the voltage.

[01:18:01]Okay. And again voltage it's the same as the potential difference. So when you see PD in exam it means voltage.

[01:18:12]Okay. And V equals to what? Equals to I * R which is ohms low ohms low. Okay.

[01:18:21]And this will lead that the relation between uh that R okay equals to V / I. So the relation usually between the current and resistance is inversely proportional like less uh more more resistance it means less current. Okay.

[01:18:42]And this also leads to the you should know the factors affecting the resistance in a cable in a wire like what the the length. Mhm.

[01:18:52]I will write here what factors affecting the resistance the length okay and for it's you can write it in this formula like R equals to uh row L / A like the resistance is directly proportional to L like if the length of wire more length it means more resistance and is inversely uh proportional to the cross-section area.

[01:19:30]So more cross-section area it means less resistance. So this is are like for now for your syllabus the two factors affecting the resistance the length of wire the length and the cross-section area.

[01:19:46]Okay.

[01:19:47]What else?

[01:19:49]Um don't forget the transformer.

[01:19:53]Transformer we have uh the power input should be equals to the power output. If we consider that the efficiency look we assume that the efficiency of the transformer 100%.

[01:20:08]So because of this the power input equals to the power output this assumption. Okay.

[01:20:14]So power is V * I and power here V * I.

[01:20:19]So this is input which is primary and the output is secondary. So remember this one. If you have the voltage and you wanted to find current.

[01:20:30]Okay. The second one to remember that the relation between the voltage and the number of turns in transformer it's directly proportional like more more number of turns it means more voltage.

[01:20:42]So if you have the secondary side is more number of turns it means more voltage it mean this is step up transformer. If the secondary side less number of turns it means less voltage it means step down transformer. So what is the formula? We can know from this relation that V the V of like let's say primary and here N primary V secondary N secondary also this is if you want to find uh number of turns okay I hope I didn't forget anything uh but please if you have any question you can write in comment you can send me uh if you need this uh file please Right.

[01:21:27]Also, and if you have any question, please just leave comment, ask me. You are welcome anytime. And good luck uh everyone. I hope the best for all of you. Okay, goodbye. Don't forget to subscribe and like and share and comment. Goodbye.