Current Electricity/Grade-12/JEE/NEET/Physics

Ajouté : 2026-05-26

[00:01:29]Hello students.

[00:01:36]Hello students. Welcome to the student brand. This is Today topic is current electricity.

[00:01:43]Today topic is current electricity.

[00:01:46]Right. Yes. So let's discuss about it current electricity.

[00:01:56]Okay.

[00:01:58]So here in this topic we will discuss about charge, quantization of charge, electric current.

[00:02:12]After that we'll discuss about conventional current, electric current.

[00:02:18]So after that uh we will discuss about electric circuit.

[00:02:23]Okay. So next one potential difference electrical potential.

[00:02:30]So after that so current drift velocity relaxation time current and relax current and drift velocity.

[00:02:41]After that we will discuss about ohmsilla. So related to resistance.

[00:02:47]So everything like uh resistance depending factors and temperature dependence of resistance restorers are connected in series and parallel. So after that we will discuss about kit of loss. After that we will discuss about electromotive force. Next electromotive force internal resistance heating effect of electric current after the cells. Likewise we will discuss one by one. Likewise we will discuss one by one. So let's start discuss about it.

[00:03:28]Let's start discuss about it. So current electricity current current electricity.

[00:03:44]Okay.

[00:03:46]So what is asset of current? Sin rate of current is ampere. Sin rate of charge is column.

[00:03:56]Sin rate of time is second. So the rate of flow of net charge the rate of flow of net charge through a unit cross-sectional area per second is called electric current.

[00:04:13]Understood or not? So the the rate of flow of net charge the rate of flow of net charge through a unit cross-sectional area per second is called electric current. I = Q by T. I = Q by T. Yes, I know. Sinate of current is ampere.

[00:04:38]Sate of current is ampere. Sinate of charge is colum.

[00:04:43]Sate of charge is colum.

[00:04:48]So assignate of time is second.

[00:04:51]So 1 ampere equal to 1 colum per 1 second.

[00:04:57]So charge and time anyway second. Okay.

[00:05:02]Sinate of charges assate of char assate of charge is colum. Assate of time is second. Assate of current is ampere. S 1 amp is defined as 1 kum of charge flowing through unit cross-sectional area per second. 1 amp is defined as 1 kum of charge flowing through unit cross-sectional area per second. So and one more point here. So I'm taking the conductor like this. I'm taking the conductor. Will only one electrons flows current is flowing. Will only two electrons flows current is flowing. So will you say only one electrons flows current is flowing? Will you say only two electrons flows current is flowing.

[00:05:44]So we can't say like this. So number of charges are moving in the conductor then only we can say current is flowing.

[00:05:52]number of charges are moving in the conductor then only we can say current is flowing. So 1 2 1 2 1 2 1 2 like this. So number of charges are moving in the conductor then we can say current is flowing. So that's why charge is quantized. What is that? Charge is quantized. Q= plus or minus N. Q = plus or minus N. So what is N? N is the number of charges. N is the number of charges. Understood or not? And one electron and one electron 1.6 into 10^ -19 kum.

[00:06:35]So in 1 kum 1 by 1.6 into 10^ -19 then you'll get 1 by 1.6 into 109.

[00:06:45]Then if you solve it, if you solve it 1 by 1.6, we'll get 0.625 0.625 into 10^ 19 that is 1 kum. Okay.

[00:06:59]So then we'll get 6.25 into 10^ 18 electron. 6.25 into 10^ 18 electrons in one column. 6.25 into 10^ 18 electrons.

[00:07:14]Is it clear or not? Once again check. So I = Q byt. I = Q byt.

[00:07:23]I = Q byt. Sin rate of current is ampere. Sate of charge is column. Sin rate of time is second. 1 amp is defined as 1 kum of charge flowing through unit cross-sectional area per second. So we we can't say only one electron 2 electron three electrons flows current is flowing. So we can say number of charges are moving in the conductor.

[00:07:44]Then in that time only we can say current is flowing. So that's why charge is quantity Q= plus or minus N. N is the number of charges and on one electron 1.6 into 10^ - 19 19 kum in 1 colum 6.25 into 10^ 18 electrons are present.

[00:08:02]Understood or not? So this is about electric current. Electric current understood or not? So coming to the next one.

[00:08:27]So we'll discuss the electrical elements. We'll discuss about electrical elements. Right? So let's discuss about it. So first one is cell positive terminal negative terminal cell.

[00:08:43]Second one is battery positive terminal negative terminal battery.

[00:08:53]And coming to the third one coming to the third one.

[00:09:04]So cell battery.

[00:09:10]Next one is so switch.

[00:09:16]This is the switch.

[00:09:35]Okay. Switch understood or not? I hope it is very clear. Cell battery open switch. Open switch and closed switch. Third one is closer switch.

[00:09:50]Closer switch.

[00:09:53]Cell battery. Open switch and closer switch. Understood or not? So coming to the fourth one. Resistor.

[00:10:04]This a resistor.

[00:10:10]Resistor is a device.

[00:10:13]Resistor is a device which is used to oppose electric current in the circuit.

[00:10:19]What is that? Resistor is a device which is used to resistor is a device which is used to oppose electric current in an electric circuit. in an electric circuit right now. So we can take fifth one real start.

[00:10:42]Rio start either we can take like this or like this also re start.

[00:10:57]So amter cell battery open switch open switch closed switch resistor your start coming to the six one ammeter Seventh one voltmeter.

[00:11:33]Next one wire joining.

[00:11:39]Ninth one wire crossing.

[00:11:44]Wire joining and wire crossing.

[00:11:52]wire crossing and the last one is the bulb.

[00:11:57]10th one is the So just check once cell battery open close switch resistor start voltmeter wing crossing and the bulb here. This is the bulb.

[00:12:17]Okay. So I hope it is very clear. Just check once all the points.

[00:12:26]First point is cell battery open switch with close switch with resistor. Resistor is a device which is used to oppose electric current. Resistor is a device which is used to oppose electric current.

[00:12:41]Resistance is the phenomena of opposing the electric current. Resistance is the phenomena of opposing the electric current. Okay. So coming to the next one. Sit of resistance is ohm. Sit of resistance is coming to the riost. Rio start is a device which is used to regulate the current. Rio start is a device which is used to regulate the current without changing the voltage source. Rio start is a device which is used to regulate the current without changing the voltage source. Understood or not? Coming to the amter. Ameter is a device which is used to measure the electric current. Ameter is a device which is used to measure the electric current.

[00:13:31]Yeah, that's why I'm thinking like this 11 should come. So where it is?

[00:13:42]So 3 4 5 6 7 8 9 10.

[00:13:55]Here it is only one.

[00:14:05]7 8 9 10 11 Thank you.

[00:14:17]1 2 3 4 5 6 7 8 9 10.

[00:14:24]Yes.

[00:14:30]Yeah. So cell battery open close switch.

[00:14:34]RIost is a device which is used to regulate the current. RIost is a device which is used to regulate the current without changing the voltage source. And amter is a device which is used to measure the electric current. Ameter is a device which is used to measure the electric current. Ameter will be connected in series combination. Coming to the voltmeter. Volultter is a device which is used to measure the potential difference voltmeter will be connected in parall combination. So anyway joining wire crossing and bulb. Okay. So these are the points. I hope it is very clear.

[00:15:11]So coming to the next one electric circuit. We'll discuss about electric circuit.

[00:15:32]electric circuit. Okay.

[00:15:48]Electric circuit is nothing but a closed and continuous path of an electric current. A closed and continuous path of an electric current is known as an electric circuit. A closed and continuous path of an electric current is known as an electric circuit. So here you can see I'm taking the bulb here. So meter like uh battery.

[00:16:21]So positive term, negative terminal current is flowing like this.

[00:16:27]Okay.

[00:16:31]Now you can see bulb.

[00:16:43]So here we have to discuss about conventional current and electric current. One is conventional current and another one is electric current.

[00:16:53]Conventional current and electric current. We have to discuss point number one conventional current.

[00:17:01]conventional current and the second one is electric current, electric current.

[00:17:13]So conventional current is nothing but the flow of positive charges. The direction of flow of positive charges will be taken as conventional current.

[00:17:23]So positive charges are moving from positive term to negative term.

[00:17:28]Whereas electrons are moving from negative terminal to positive terminal.

[00:17:33]Okay. Conventional current. So here you can see charges are moving like positive charges are moving from positive charges are moving from positive term to negative terminal whereas electrons are moving from negative termal to positive termal. So that is nothing but so positive charges are moving from high potential to low potential that is positive terminal to negative terminal negative terminal understood or not. So that is about conventional current conventional current. So what about electric current? Electric current is nothing but the rate of flow of okay anyway so charge that we know that but here flow of electrons the direction of flow of electrons will be taken as electric current. So electrons will be moving from low potential to high potential that is nothing but negative terminal to positive terminal negative terminal to positive terminal understood or not. So this is about conventional current and electric current.

[00:18:36]Conventional current and electric current. Understood? So I hope it is very clear. So coming to the next one, coming to the next point that is so based on the based on the magnitude based on the magnitude and direction based on the magnitude and direction of current. So current will be divided into two parts. One is DC. Another one is AC.

[00:19:15]One is DC.

[00:19:17]First one is DC.

[00:19:20]Second one is AC.

[00:19:22]So DC magnitude and direction does not change with respect to time. Magnitude and direction does not change with respect to time. That is called direct current.

[00:19:36]So coming to the AC magnitude and direction changes with respect to time.

[00:19:43]Magnitude and direction changes with respect to time. So that is called alternative current AC. Okay. So DC example cell battery cell battery coming and DC dynamo DC dynamo coming to the alternative current both magnitude and direction changes. So example AC dynamo AC dynamo understood or not? So this is the B DC and AC.

[00:20:20]Okay.

[00:20:21]Is it clear or not? So DC cell battery DCO coming to AC AC dynamo. Is it clear or not? So now you can see if the charge is moving in a circular path. So charge Q is moving a circular path with the frequency F. So I = QF.

[00:20:44]If the charge is moving a circular path with the frequency F. If charge is moving a circular path with frequency F.

[00:20:52]So then I = QF. I = QF. Is it clear or not? Yes. So next one.

[00:21:17]Next we will discuss about drift velocity and relaxation type.

[00:21:23]drift to velocity and relaxation type.

[00:21:26]Right. Drift to velocity.

[00:21:32]Drift to velocity and relaxation time, drift velocity and relaxation time. Is it clear or not? Yes. So now you can see relaxation time.

[00:21:59]So time is not visible time.

[00:22:07]So drift to velocity and relaxation time. So normally when electrons are moving in a conductor when electrons are moving in a conductor experience force as I know when electrons are moving in a conductor it experience force. So here I'm taking like this.

[00:22:28]So current is moving this direction.

[00:22:30]Electrical field will be here. Okay. So electrons are moving in this direction.

[00:22:36]Electrons, electrons, electrons, electrons, electrons, electron. So WD will be like this.

[00:22:45]Drift to elasticity. Drift to elasticity will be opposite direction. Understood or not? Yes. Now we can see f = f = e q or f = q.

[00:23:03]Yes or no?

[00:23:28]Is it clear or not?

[00:23:31]Then f = m a f = m a then we can take m a = eq or q then a = eq by m or q by m q by m understood or not? So now we'll discuss about drift to velocity. First of all we have to discuss about drift to velocity.

[00:24:06]Okay. So after that relaxation.

[00:24:10]So drift to velocity.

[00:24:12]Drift to velocity.

[00:24:33]So coming to drift to velocity like normally when electrons are moving in a conductor so they are moving in a closed enclosed path. Okay. So electrons are moving in a closed enclosed path. Right?

[00:24:49]S like this they are moving that two many electrons are moving. Many electrons are moving. What happens? One electron is going to eat another electron. That electron is going to another electron. Like that keep on collisions will takes place. Keep on bombardment takes place. Yes or no? Keep on collisions will takes place.

[00:25:10]So like before collision the electron is moving to some velocity after collision electron is moving some velocity. Yes or no? So there is a change before and after like that each and every collision the velocity of an electron changes. So the average velocity of an electron moving in a conductor is called drift velocity. The average velocity of an electron moving in a conductor is called drift velocity.

[00:25:46]Okay. So that is one point. Coming to the relaxation time. What about relaxation time?

[00:25:52]Relaxation time is nothing but So as I said electrons are moving in a closed path. So collisions will takes place. So will collisions takes place regularly or randomly.

[00:26:08]So yes. So after 1 minute one more collision after 2 minutes one more collision after 3 minutes one more collision like that collision will not takes place. Right? So it takes place at random interval. Okay. At random interval one collision after that another after that another. So collisions may not takes place at regular intervals but it takes place random intervals.

[00:26:31]Is it clear or not? Yes. So between one collision to another collision there is a time gap. So immediately the collisions will not takes place all at a time. Right? So there is a time gap between one collision to another collision. between one collision to another collision? Yes or no? Yes. So the average time gap between two successive collisions, the average time gap between the two successive collisions is known as relaxation time.

[00:27:02]That is called relaxation time.

[00:27:04]Understood or not? I hope it is very clear. These are two points are very very important. So next one we will discuss about current and drift velocity.

[00:27:28]current and drift velocity.

[00:27:32]So here I'm taking this the conductor.

[00:27:38]Okay. So here current is moving like this.

[00:27:44]electron. So electric field.

[00:27:47]So actually within the particular volume we are taking this a particular uh area.

[00:27:53]This is a particular area area and here also particular area area and this this volume volume.

[00:28:08]So electron is moving here.

[00:28:14]So is it clear or not?

[00:28:27]Yes. So now you can see electron moving opposite to the electrical field. So velocity equal to displacement by time taken. Velocity is nothing but v l by.

[00:28:44]So this time interval we are taking. So that's why time interval that is delta t. So l = v d into delta t.

[00:29:02]L = V D into delta T. Understood or not?

[00:29:07]Yes. So now you can see here.

[00:29:11]So volume of the conductor length into area length is nothing but W D into delta T into A.

[00:29:22]So V = V = volume of the conductor V D delta T into A.

[00:29:32]Okay. Number of electrons present in the particular volume. Okay. Number of electrons present in the particular volume. So that is so we can see here number of electrons number of electrons present in a particular volume that is so small n is electron density small n is electron density understood or not small n is the electron density so n into v d into delta t into N into V D into delta T into A. Is it clear or not? Yes. So now you can see quantization of charge delta Q = N V D into A N V D into A right into E into E. Quantization of charge Q= N S O. So now I = delta Q by deltat T that is N B D delta T into A by delta T. So delta T delta T get cancel delta T delta T get cancel. So the remaining I = to I = N E A V D N E V D A Okay. So what about current density? Current density equal to current density.

[00:31:23]Current density equal to J = I by A I by A. So j = i by a i = how much? N e a v d by a. So a get cancel.

[00:31:40]J = n e v.

[00:31:44]Is it clear or not? Just check once.

[00:31:48]So let me know if you have any doubts.

[00:33:20]Okay. So this is about current density.

[00:33:34]Now let's discuss about So now we'll discuss about let's start oh so is nothing but so here you can see so I'm taking the restor Restor is flowing as I said the voltmeter will be connected in parall combination.

[00:34:55]Ultimator will be connected in parall combination. So the potential difference across the ends of the given uh given metallic conductor the potential difference across the ends of the given metallic conductor is directly proportional to current flowing through it. V is directly proportional to V = I.

[00:35:20]V is directly proportional to I. V = I at a constant temperature and physical conditions also same. At a constant temperature and physical conditions also same. Once again here you observe. So the potential difference across ends of the given metallic conductor is directly proportional to current flowing through it. V is directly proportional to Val.

[00:35:45]Okay. So that at constant temperature and physical conditions also same conditions are very important. And now you can see Ohm's law gives the definition of resistance. Oh gives the definition of resistance.

[00:36:02]Okay. Yes. So here R = V by I R = V by I. Is it clear? Right. Now so so we'll do some okay how to do the activity so for doing ohms law what are the materials required so how to connect what is the circuit diagram how it will be and uh what is the graph everything we'll discuss now you can see materials required materials required What are the materials? First one is first one is four cells.

[00:36:50]Four cells 1.5 volts of each.

[00:36:55]And coming to the second one necro necro so 0.5 m length.

[00:37:06]And coming to third one micromeire of 0.5 m length understood or not? So ameter ameter fourth one is voltmeter and the fifth one is switch and coming to the sixth one connecting wires.

[00:37:39]Okay, these are the materials required.

[00:37:42]These are the materials required. Once again, check four cells 1.5 volts of each necro wire, ameter, voltmeter, switch and connecting wires. Is it clear or not? Yes. Now circuit diagram.

[00:38:13]Now I'll draw the circuit diagram. Check once.

[00:38:27]circular diagram.

[00:38:30]Okay. So here four cells 1 2 3 4 am a meter.

[00:38:47]So resistor Okay.

[00:39:25]So now you can see here first you have to connect one cell.

[00:39:33]First you have to connect one cell and note down the reading of amter and voltmeter.

[00:39:38]So second one connect to two cells.

[00:39:43]Connect two cells and note down the reading of ameter and voltmeter.

[00:39:48]First you have to connect one cell 1 2 3 4 four cells. So dotted lines represent we are connecting one by one. So first you have to connect one cell and wrote down reading of amter and voltmeter.

[00:40:02]Next connect two cells and note down reading of ometer and voltmeter. So repeat the process for three and four.

[00:40:09]Repeat the process for three and four cells.

[00:40:13]understood or not? If you repeat the process for three and four cells and observe the reading of amit reading and volt reading and mention in the tableler form. So I'll give the tableler form. So I have to mention in that okay so just check once.

[00:40:38]So this is the table form.

[00:40:46]Serial number of cells reading ultimate reading V by form.

[00:40:51]Serial number 1 2 3 serial number of cells am reading ultimate reading V by = R 1 2 3 4 1 2 3 4 Okay. This I have to mention in the table form and draw the graph for V I.

[00:41:18]So the graph V on Yaxis I on X-axis the graph is straight line for omic conductors.

[00:41:27]Okay for omic conductors the graph is straight line omic conductors the conductors which obey ohms law and coming to the nonomic conductor the graph is curve like this we are on yaxis I on x-axis nonomic conductors nonomic conductors right nonomic conductors So omic conductors and nonomic conductors for omic conductors the conductors which obey those are called OB conductors. The conductor which does not have those are called nonomic conductors. Is it clear or not?

[00:42:16]Yes. So next one.

[00:42:41]So now we will discuss about resistance and resistivity. So first of all we have to discuss about factors depends on resistance. Factors depends on resistance. So here AB AB then battery switch.

[00:43:16]So current is moving.

[00:43:18]So you have to place first you have to take first you have to take the nicro wire first case length and area of the cross-section second one twice the length of the crosssection and area of the cross-section twice the length and area of the cross-section is same and coming to the third one area of the cross-section is doubled Twice of the area of the cross-section length is L. And in the last case, so we are taking nic sorry here copper wire.

[00:44:05]So in the first three cases we consider nicro 1 2 3. So in the three cases I took nicro. Okay.

[00:44:18]So only in the fourth case I'm considering the copper wire because I'm changing the material. So in the first two cases you observe I increase the length. In the sec 1 three. So first and third case area of the cross-section is increased and in the fourth case if you observe material also changed. So by this we can understand if you observe the reading of ameter when you are connecting each and every time 1 2 3 the four cases we can observe length resistance is directly proportional to length of the conductor. Resistance is directly proportional to length of the conductor. Resistance is inversely proportional to area of the cross-section. As length increases, resistance also increases. As area of the cross-section decreases, resistance increases. Inversely proportional.

[00:45:14]Right? So here you can see R is inversely proportional to area of the crosssection. R is directly proportional to L by A. R= row into L by A. Row = A by L. Row = A by L. Resistivity equal to. So there is one definition. So definition also we have to discuss definition of resistivity. Resistivity is equal to resistance of the conductor per unit length and unit cross-sectional area. Resistivity equal to resistance of the conductor per unit length and unit cross-sectional area. By observing the formula we can get to know the definition. And by observing the formula we can get to know the definition understood or not. So now resistance.

[00:46:28]Resistivity.

[00:46:37]So resistance and resist differences we'll see point number one R is directly proport R is inversely proportional to area R is directly proportional to L by A. So like this and coming to the resistivity row = A by L R A by L. Is it clear or not? Now S of resistance is ohm.

[00:47:19]And coming to the next one here you can see assignate of resistance is ohm symbol is oh. Now resistance depends on temperature and resistance depends on nature of the material.

[00:47:44]nature of the material and coming to the resistivity.

[00:47:53]Yes s is ohm meter and the symbol is so resistivity depends on temperature and resistivity depends on nature of the material.

[00:48:15]Is it clear or not?

[00:48:18]Just check once resistance and resistivity.

[00:48:32]Resistance and resistivity.

[00:48:36]So I hope it is very clear.

[00:48:45]So next one temperature dependence of resistance.

[00:49:15]temperature temperature dependence of resistance.

[00:49:20]Since so normally I will tell two points. So when temperature increases free electrons in the conductor also increases.

[00:49:32]Free electrons in the conductor increases they will move with a greater amplitude they'll move with a greater amplitude. So as soon as temperature increases movement of the electrons increases. So then that time resistance and resistivity decreases conductivity increases.

[00:49:50]So when they're moving to greater amplitude collisions will takes place.

[00:49:55]So collisions will move in the conductor. So resistance and resistivity increases conductivity decreases. So finally overall we can take we can say when temperature increases resistance and resistivity also increases. When temperature increases resistance and resistivity also increases. Right? Yes.

[00:50:20]No.

[00:50:33]Alpha is the temperature coefficient of resistance.

[00:50:37]Alpha is the temperature coefficient of resistance.

[00:50:41]So, R = R + R into alpha into T - T.

[00:50:50]Then r - r = r t - t plus alpha = r - r by r into delta t. We can take delta t.

[00:51:10]And coming to the resistivity also row - into delta t.

[00:51:20]Is it clear or not?

[00:51:23]So I hope it is very clear. Just check once.

[00:51:27]Next.

[00:51:29]Resistors are connected in series.

[00:51:38]Resistors are connected in series then resistors are connected in parallel.

[00:51:44]Resistors are connected in series then resistors are connected in parallel.

[00:51:48]We'll discuss resistors are connected in series.

[00:51:54]Resistors are connected in series combination.

[00:52:05]series combination.

[00:52:17]Okay. So here I'm taking resistors 1 2 3 R1 R2 R3 across R1 V_sub_1 across R2 V2 across R3 V3.

[00:53:07]Okay. So now you can see current I = I1 = I2 = I3 = I. So current is same current is same throughout the path throughout the circuit. So potential difference B = I from Ohm's law V S = V1 + V_sub_2 + V_sub3 V = V_sub_1 + V_sub_2 + V3 so I = I R1 + I R2 + I R3 so I am taking common R1 + R2 + R3 I A get cancel then RS = R1 + R2 + R3 RS = R1 + R2 + R3 understood or not?

[00:54:14]Yes. If n number of resistors are connected in series combination then rs equal to nr rs equal to nr. So next we'll discuss about resistors are connected in parallel combination.

[00:54:57]resistors are connected in parallel.

[00:55:07]So now So here you can observe.

[00:56:00]So potential difference is same but current is dividing. Yes or no?

[00:56:07]Potential difference is same but current is dividing.

[00:56:11]Then we can take Now v = v_sub_1 = v_sub_2 = v3 = v. Then we know that ohm's law v = I = v by r. So then I = I1 + i2 + i3. Then V by RP = V by R1 + V by R2 + V by R3.

[00:56:50]V by R1 + V by R2 + V by R3.

[00:56:58]Now v I'm taking common 1x r1 + 1x r2 + 1x r3. So we will get cancel. So the remaining value is 1x rp = 1x r1 + 1x r2 + 1x r3.

[00:57:24]If n number of resistors are connected in parall combination.

[00:57:29]If n number of resistors are connected in parall combination 1 by rp = n / rp = r by n.

[00:57:41]If n number of resistors are connected in par combination. Chin.

[00:58:11]Okay.

[00:58:21]Okay. So, next one So now we'll discuss about kit of laws.

[00:59:17]So here in kit of laws there are two laws are there.

[00:59:22]One is junction law.

[00:59:26]So second one is loop law.

[00:59:31]Junction law and loop law. What is junction law? Sum of the currents reaching to the junction equal to sum of the currents leaving from the junction.

[00:59:40]The algebraic sum of all the currents reaching at a junction equal to zero.

[00:59:45]Okay. So I'm taking here this the current I1 I2 I1 I2 I3 I4.

[01:00:01]Okay. So now you can see I1 + I2 = I3 + I4.

[01:00:11]So that is about junction law.

[01:00:15]So junction is a point in a circuit.

[01:00:19]So where two or more conductors will meet.

[01:00:22]Okay, that is junction law. And coming to the loop law.

[01:00:30]Loopla.

[01:00:37]Loopla.

[01:00:51]So loopla here there are four points are there in loopla. So just check once loopla right.

[01:01:07]Yes. So pi number one.

[01:01:15]So this the cell positive 10 negative 10. So this the path when you are moving through the cell. So from positive 10 to 10 ml. So the emf is negative because you are moving to the negative end. Okay. So coming to the again same if you are moving from negative terminal to positive terminal then emf of this cell is positive. Coming to the third one this is a resistor current direction.

[01:01:54]So when you're moving in the same direction of the current flow the I term is negative.

[01:02:02]I term is negative.

[01:02:05]So next one fourth one when you are moving opposite to the current direction.

[01:02:11]So this is the resistor current uh so you are moving opposite to the current direction. The VR term is positive. I term I term is positive.

[01:02:25]Okay. So that is potential. So this is about loop.

[01:02:30]So, so every each and every circuit may not have to reduce into simple series and parallel that I'm will use of junction law and loop law. These four points are very very important you have to follow you have to use while writing an equation.

[01:02:51]Okay. So next here so we have one more doubt that is s what is emf?

[01:03:00]What is emf of this cell?

[01:03:07]Emf of this cell is nothing but so e now generally this is a cell.

[01:03:17]So switch so your resistor.

[01:03:24]So current is passing like this.

[01:03:27]We know that as soon as you on the switch the current start flowing positive positive terminal to negative terminal.

[01:03:36]What if the charge is at negative terminal?

[01:03:40]Okay. In order to bring the positive charge to negative terminal what influence is what influence is making the positive charge to move from negative terminal to positive terminal from lower term lower potential to higher potential. Okay. The work done to bring unit positive charge from lower potential to higher potential. From negative termal to positive terminal.

[01:04:05]Okay. The work done to bring unit positive charge from lower potential to higher potential from negative terminal to positive terminal is called emf of the cell. Okay. The work done by the cell on the charge to bring from negative terminal to positive mass.

[01:04:25]So E = W by Q = W by Q I hope it is very clear. So what is MF? What is U.

[01:04:49]So now EMF is completed. So kov last completed.

[01:04:56]Next internal resistance is there. So when electron is moving through electrolyte it experience some force some resistance some opposition. Okay. So in the cell in the cell when electron is moving through electrolyte it experience some internal resistance. Okay. Some opposition that is called internal resistance.

[01:05:19]Okay. So emf of the cell at the same time internal resistance will be there.

[01:05:24]MF of the cell at the same time internal resistance will be there. Is it clear?

[01:05:30]Yes. Now can see.

[01:05:36]So now heating effect of electric current.

[01:05:41]We'll discuss heating effect of electric current.

[01:05:47]Heating effect of heating effects of electric current electric current.

[01:05:59]So, V = W by Q W = VQ V = W by Q W = VQ.

[01:06:11]So P = W by T VQ by T that is you know Q byt is current.

[01:06:22]So V into I so P = VI whatever the energy is given to the conductor that will become in the form of heat.

[01:06:35]So H = V I into T.

[01:06:41]Now V = I right V = I substitute here H = I into I into T then you'll get H = I² RT.

[01:06:55]Heat produced in the conductor is directly proportional to square of current. Heat produced in the conductor is directly proportional to resistance.

[01:07:05]Heat produced in the conductor is directly proportional to time.

[01:07:10]Okay. So this about heating effects of electric current and also known as J's law of heating correct.

[01:07:20]So that is true. Sun 01 flower. Correct.

[01:07:27]So heating effect of electric current also known as J's law of heating. Heat produced in the conductor is directly proportional to square of current. Heat produced in the conductor is directly proportional to resistance. Heat produced in the conductor is directly proportional to time.

[01:07:47]Okay.

[01:07:49]So the amount of heat will be given to the conductor by that only heat will be produced.

[01:07:59]Yes or no? So without sending the current how it will be produced? Best example heater, iron box and electrical cooker.

[01:08:12]So the amount of Okay. So now let's discuss about cells are connected in series.

[01:08:26]Cells are connected in parallel.

[01:08:29]Cells are connected in series.

[01:08:34]connected in series.

[01:08:43]So now you can see Okay. Now cells are connected in series combination.

[01:09:14]Cells are connected in series combination.

[01:09:22]Now net emf net emf equal to any Net internal resistance that is equal to NR.

[01:09:44]So external resistance external resistance equal to capital R.

[01:09:57]Total resistance Total resistance = NR + R.

[01:10:10]Then I = NMA by NMA by total resistance that is N E by N R + R that is I.

[01:10:40]Okay.

[01:10:42]So coming to the next one. If cells are connected in parall combination.

[01:10:48]If cells are connected in parall combination how it will be? We'll see.

[01:12:00]Okay.

[01:12:02]So net emf net emf equal to e net internal resistance equal to r by n.

[01:12:26]External resistance External resistance equal to R. Total resistance R by N + R.

[01:12:51]So now I = to net emf by net or total resistance.

[01:13:05]Net emf by total resistance.

[01:13:19]So I = E by R by N + R.

[01:13:31]Okay. So now you can check So thank you so much for joining and attending listening giving an opportunity to teach. This is your Sabbasa signing off. So if you like the content do like share and subscribe to student de brand. So if you like the content so you can share to your friends ask your friends to join to the class.

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