00:00 Good students, this is Eme Nnamdi John, I will be taking us on physics, on the topic electric field.

00:20 Now, electric field, we'll talk about the electric cell.

00:26 Electric cell is a device used to supply electric energy.

00:33 We have two types of cells, we have the primary cell and the secondary cell.

00:38 Now, the primary cells are cells whose chemical reactions are irreversible.

00:44 That is, they can be recharged.

00:49 They cannot be recharged.

00:51 And examples of it is Daniel C. and Liquid C.

00:56 Now, we have the secondary cell, these are cell whose chemical reactions are irreversible.

01:03 And that's why they are being recharged.

01:07 Examples of it are lead acid and alkaline accumulator.

01:14 Now, we'll talk about electromagnetic force, which is called the EMF.

01:19 We said these can be defined as the total work done in moving a unit charge around the entire circuit.

01:27 It is measured in volts.

01:30 It is arranged in two ways, which is what the cities are in parallel.

01:37 Now, the cities form, we are told that what they are joined end to end.

01:42 That is, we have it to be like this.

01:46 They are joined end to end, which will have the positive, we have the negative, we have the positive and we have the negative.

02:05 Now, we are told that parallel, these are the cell that are arranged side by side.

02:11 That is, we have it to be like this.

02:15 This is the cell, this is another cell, and this is another cell.

02:29 We have our EMF here, we have our EMF, we have our EMF, we also have EMF here, we also have the EMF.

02:38 This is it.

02:41 Now, we'll talk about current electricity.

02:44 Current electricity, now we'll talk about the terminology on that current electricity.

02:49 We have the first one, electric current, it is the reach, a switch charge are transported.

02:56 We have the I, is equals to the charge over the time, which we have Q, is equals to Q, is equals to I, T, where Q is the charge, I is the current, and T is the time.

03:12 Current is killer, quantity, and it is measured in ampere, current is measured in ampere, all right?

03:25 Ammeter, we said ammeter is a device used to measure the currents, and it's an ID, ammeter almost half negligible resistance,

03:35 I must be connected in series to the circuits. We have the potential difference, which is also called the voltage, and it is defined as work done in moving a unit charge from one point to another.

03:50 We have the resistance, this can be defined as the ability for a material to convert electric energy to heat energy.

03:59 It is measured, it is a measure of opposition to the flow of current around the circuit, and it is measured in ooms, measured in ooms, with a symbol like this, ooms.

04:15 Now we have the EMF of a cell, we said, we are told that EMF of a cell is a total energy which a current flows through the internal resistance of the cell, and external resistance of the circuit.

04:27 We have these, we have the EMF, EMF is of course, the current opposition to the internal resistance plus current opposition to the external resistance, we have EMF,

04:49 is of course, I into brackets, R plus B, R, now this for the EMF. Now, this course about the lost votes, this can be defined as a potential difference across the internal resistance of the cell, which you have these two words.

05:07 EMF, that is the lost votes as this, which is equal towards I small R, as the lost, this is called the lost votes.

05:26 Now, arrangements of resistors, resistors can be arranged in two forms, we have the series arrangements, we have the parallel arrangements.

05:40 Now, under the series arrangement, it's arranged with the diagram like this, we have this, one, we have this, two.

05:56 Now, for the series arrangements to hold, we are told that we have equal amount of current that flows through them, the current that flows through this place is equal to the current that flows through this place.

06:07 So, we have equal amount of current that flows through this. B in the total vote, the total vote is equal to the song of the potential difference across each, which you have that was, the V total is equal towards V1 plus V2 plus V3 and so on.

06:30 Now, the current, we have I total is equal towards I1 is equal to I2 is equal to I3.

06:44 Now, we have that was, we have R total is equal towards R1 plus R2, that is how to get the total resistance when we are told for series arrangements.

07:01 R1 R2 equals R1 plus R2 or we can have this R2 equals R1 plus R2 plus Rn and so on and so forth.

07:21 We have the parallel arrangements, these are the arrangements that are arranged side by side.

07:28 Now, we have the diagram to be like this, like this, with the cell on it, we have power 1, we have power 2, we have power 3 and we are told that the total current is equal to the sum of the current in the resistor.

07:58 That means we have I total is equal towards I1 plus I2 plus I3 and so on and so on, there are many of it.

08:11 We are told that they have equal potential difference, that is we have V total is equal to V1, is equal to V2, is equal to V3 and so on.

08:23 Now, we have the resistor towards 1 over R total is equal to 1 over R1 plus 1 over R2 plus 1 over R3.

08:38 Now, this is a way to solve for the parallel resistance.

08:49 We have principal potential meter, now this is a device that is prepared to measure potential difference.

08:55 It is apparatus commonly used to measure and or to compare the EMF, to compare EMF.

09:04 It can also want to compare the resistance to measure resistance, you can use to measure resistance, I also can use to compare the EMF of the cell.

09:14 Now, we have the resistivity and condotivity.

09:18 Now, under the resistivity we are told that this is a material that is used to measure the opposition or the flow of current around the material.

09:30 Now, the factors that affect resistivity, we have one, we have the length, which is the resistance, is proportional to the length, which is what's L.

09:45 And the next one, we have the area, that means the resistance is inversely proportional to the area.

09:54 Now, also, we are also told that what that temperature can also affect the resistivity, that means the increase in temperature will also increase the resistivity.

10:06 The increase in the length will also increase the resistivity and the increase in the length, increase in the resistance will bring a decrease in the area and vice-versa.

10:22 We also have nature of the material, nature of the material is a free electron on the surface of the material, we affect the resistance of such material.

10:32 Now, we have this from the resistivity, we have resistivity is direct proportional to the length and inversely proportional to the area.

10:48 That is, we have this by removing this proportionality sign, we have, which is equal towards, we have called the rule L-A.

10:59 Now, from here, we have R-A is equal to R-L and R-U is equal to R-A over L.

11:12 Now, this is the resistivity and it is measured in oomps meter.

11:19 So, for we to get the resistivity, we have the resistance multiplied by the area over the length.

11:28 Now, what we are told about conductivity is the reciprocated of the conductivity is the reciprocated of the resistivity.

11:36 That is, we have the conductivity to be like this, because we are told it is reciprocated, which we give us our length.

11:45 Okay, let's see.

11:50 That is what.

11:51 One over the resistivity, which we give us that this is equal towards, one over the resistivity that we have here is what.

12:06 R-A over L, that is L, can come towards this side.

12:12 We have the resistivity is equal towards, conductivity is equal towards length over R-E.

12:23 This measure is on, you know, same as...

12:33 All right, that is for the conductivity.

12:39 Now, we have electric field.

12:45 Now, on electricity, we are told that electricity is a region where forces are being experienced, where electrical forces are being experienced.

12:56 Now, we are concerned of charges. Now, we are told for a body to be positively charged, the body has to have excess positive in it and less amount of negative.

13:07 Likewise, when we talk about the negativity, we are told that the body said to be negative when it has excess amount of negative and less amount of positive.

13:17 Now, a body said to be neutral when it has equal amount of...

13:20 Now, a method of charging a body, we have three methods of charging a body, we have charge it by contact, charge it by friction and charge it by induction.

13:30 Now, charging by contact, a body said to be charge, charge body when it is what, when a charge body is brought close to what?

13:39 You know, charge body, and this true body attains, or the charge body is being transferred to another charge body, and this body becomes equal.

13:50 Now, charging by friction, for a body to be charged negatively, we are told that what, charge body can be produced by rubbing an ebonitroid with a foil.

13:59 Now, for a little charge, a positive body, you said, a body can be charged when produced by rubbing a glass with a sink, you can produce a positive charge body.

14:11 Now, for a little charge, a body by inductor, or induction, sorry, we are forced there for this body to be charged.

14:19 The force, we have a body to be this, the body is this, we have this body, we have positive, we have negative, we have positive, we have negative, we have positive, we have negative, we have positive, we have negative.

14:39 Now, this is a charge body that comprises of what, the positive and the negative charge.

14:44 Now, the first step we are told, that, to charge a body by induction, four steps are to be considered.

14:52 Step, step for charging a negative body.

14:56 Now, for we to charge a negative body, you can charge a negative body, you can charge a positive body.

15:01 Now, for we to charge a negative body, the four steps is, bring a positive charge, a positive charge body, which is what?

15:11 Which, charge body, which is on a benign throat with positive, positive charge body, close to the body.

15:20 Now, we will bring this positive charge body, close to the body, this step to set out from here, you can have these, we have negative, negative, negative, we have positive, positive, positive, positive.

15:42 Now, with this, now, you can see that, now, that the positive side, as a repair bar, why the negative side is attracting towards to this part, which is what?

15:57 Now, the second root, we have to bring what, now bringing what, and etching to the body, which is the third one, the second one.

16:20 Now, we have these, etching is carried out on these, etching is carried out on these, we have the etching, this is etching, and the body is this.

16:48 Now, etching is carried out to neutralize this one, we have it to be, to be like this, we have positive, which is this, neutralizing the body,

17:12 Now, bringing this, now, you remove your hand, which is what? The etching, remove the etching, we have these.

17:25 Now, the fourth one now, we are towards, remove the positive rod, the positive rod, which is this, removing the positive rod from it, we have everything to be like this.

17:38 That is, we have produced a negative charge body, as we produce. Now, from there, we can produce a negative charge body.

17:50 Same thing is applicable, if we want to produce for positive charge body, what we need to do is to use a negative ebonite rod,

18:00 to place it at the body, we can also produce a positive charge body, the same procedures we can use to get the positive charge body.

18:11 Let's proceed, concepts of electric feed, concepts of electric feed, electric feed, like we said, it is a region where electric feed are being experienced, or they are being filled.

18:28 Now, we are to that was, electric feed are vector quantity, what are vector quantity, the magnitude and what's the half size.

18:37 Now, on the electric feed intensity can be defined as the ratio of the force to the charge, the ratio of the force to the charge, electric feed intensity, is the ratio of the force to the charge, which is q.

18:51 We have this as it was as the electric feed intensity, as force, over the charge.

19:02 Now, as I said notes, the direction of the electric feed, pointing away from the positive charge, but points towards the negative charge body.

19:14 That means we have, so this is like this, let's say this is a positive charge body, this is a negative charge body.

19:26 Now, the positive charge is pointing away, that is, is pointing away, is pointing away.

19:38 Why this is pointing inward, is pointing inward, is pointing inward, that means we can have it to be like this, that charge body, and the negative charge body.

20:02 That means if I move them like this, from this place, we have it moving out, going into this, we have this coming in, coming in, that is what, the positive charge body and the negative charge body.

20:29 Now, we have the columns law, columns law state that the electrostatic force between two charges, is directly proportional, is directly proportional to the product of the masses, M1 and M2, and inversely proportional to the square of the distance apart.

20:50 Now, which we have to be this, that's K, we have the F is equals to this, this is how to solve it, we have this as the charges, then substitute to get the charge.

21:07 Well, let's go back to this, which you have, is equals to F over Q. Now, what is our F giving to us? We have it here to say that Q1, Q2, Q2 over R squared times R, Q. This can take care of this, we have R, this, with this R.

21:34 Electric field intensity, which is what? Q, K, Q over R squared, this is for electric intensity, and K is equals to 1 over 4 by E nodes for the K.

21:58 Let's proceed. Now, electric potential, electric potential, it is a work done in moving a unit charge from an infinity to a point of consideration.

22:13 And we have the formula to be given us, V is equals to W over Q, and W is equals to V more than Q. We have electric potential, it is a scalar quantity, and it can be expressed mathematically as the product of the electric field intensity, and the distance.

22:34 Now, for me, we have this as the potential, and we have this as E, and this as the distance. Now, from electric potential, we already have to vote Q over 4 by R squared, and the D is equals to R.

22:53 Now, by that, we can substitute everyone into this, we are to get this. Now, let's talk about capacitor.

23:03 Capacitor is a device used for storing charges. Capacitor is also called condenser. We will also say that capacitor is very proportional to the potential difference across E, which will have the Q is very proportional to what to V,

23:21 and Q is equals to CV, where the C is a constant called the capacitor of capacitance, and we have the other ones, which capacitor is measured in Farand.

23:35 Now, factors that affect capacitance of a parallel plate, we have the area, the area also affects the capacitance.

23:45 We have the distance between the plates affect the capacitance. We also have the nature of the dielectric material. These are the three functions that affect the capacitors in a parallel plates.

24:02 Now, capacitor, sorry, capacitor is arranged in two forms. We have the series arrangements, and we have the parallel arrangements.

24:12 Now, the series arrangements, we are told that what they are arranged side by side, that is, we have it to be like this, side by side, side by side, this is how it is.

24:28 Now, we are told for a capacitor in a series, we have the stored equal amount of charges. That means we have equal amount of charges towards Q, Q1,

24:41 Q2, equal amount of charges. Now, the big thing is that total voltage of the circuit, we have total voltage, is equal to the sum of the potential difference, which is what V is equal to V1 plus V2 plus V3.

25:03 Now, for this, now, one of the series we have was 1 over c, total is equal to 1 over c1 plus 1 over c2 plus 1 over cn.

25:20 Now, this is a formula to solve for parallel for series arrangements.

25:28 In the parallel arrangements, in the parallel arrangements, they are being arranged side by side, they are arranged side by side.

25:41 That means for this to hold, for which to know about this, for which to take the following points, we are told that what they have equal amount of voltages.

25:51 We have the voltage, V, total is equal to V1, is equal to V2, is equal to V3.

25:59 And we are told that what the total charges is equal to the arithmetic charges, which is what Q, total is equal to Q1 plus Q2 plus Q3, and so on, plus Qn.

26:16 Now, for the parallel arrangements, we have that what c2 is equal to c1 plus c2 plus c3 plus cn.

26:31 That is the formula to solve the capacitor in the parallel arrangements.

26:38 Now, energy stored in the capacitor, we are told that what it is half the potential difference and the charge, which you have as thought as the average, which is what's half the potential difference and the charge, which you have all these.

26:56 Now, from there, we already know that Q, Q is equal to CV, from there we can impute it to get other functions, which you have that half of the CV square, which is this one.

27:08 Also, we can also go down to say that V is equal to Q over C. Now, by substituting this into this first place, we are going to have this, and by that we have as E is equal to 1 over 2, Q square over the capacitor.

27:28 Now, let's move forward. To talk about the uses of capacitor, they are used for storing charges, they are used for storing electrical energy, they are used for detecting, they are used for essential components in our radio, in our television, computer panels.

27:47 They are used limiting the value of, limiting the value of current flowing in the AC circuits. Now, let's talk about the conduction to liquid and gases, conduction to liquid.

28:03 All right, electrolysis gives the chemical chain in the liquid due to the flow of electric current. Right? Some liquid are good conductors, why others are poor conductors of electricity, and good conductors of electricity are electrolytes, why poor conductors of electricity are non-electricities?

28:30 Liquid such as solution of acid, base and source are generally good conductors, liquid such as benzene and paraffin are poor conductors, organic compounds are generally poor conductors, why pure conductors are also pure conductors?

28:54 Okay, let's see. Now, application of electrolysis is applied in several industries, for example, in the electrolyte plates of metals and in pure metals.

29:14 Now, on the electrolyte plates, this is the process of costing a metallic object with another metals, in order to improve the appearance or to safeguard it against corrosion.

29:30 Now, we'll talk about far this law.

29:34 Far this law states that the mass is directly proportional to the quantity of the electricity, which we have m is directly proportional to q, and m is equal to what?

29:45 Remove this proportionality sign, we have z q. q is equal to what? The electricity, which is what?

29:51 i, c, y, z is the constants, which you have that word, m is equal to z, i, c.

30:06 Nice. We have it here. Now, the second law states that the mass, the mass is of different substance deposited or liberated by the same quantity of electricity.

30:18 A directly proportional to the chemical equivalent of that substance, which you have that word, that m is directly proportional to q, and q is equal to i, c, and m is directly proportional to i, c, and m is equal to z, i, c.

30:40 Now, z is a constant of the proportionality, which is known as what? Electrochemical equivalent, which is called the e, c, e, of a substance.

30:53 It is the mass of that substance deposited by one column of electricity in a process of electricity, c.

31:03 That means we have that word, that z is equal to what m over i, c.

31:13 Let's keep this one. It's also important for us.

31:17 Then we'll talk about conduction of electricity through gas, where through that conduction of electricity through gas, gas is studying, is the study using a discharge tube.

31:28 This process of a long gas tube, with meta-electro-c to each end of the tube.

31:40 Now, we'll talk about what the hot cathode, the harmonic emission, and thus discharge to cathode ray are produced from a cold cathode.

31:55 Another way of producing free electron is from hot cathode.

31:59 Whenever a meta is heated to a sufficient high temperature, electrons are being emitted at the surface of that meta, which is also known as what?

32:12 Thamonic emission. That means Thamonic emission is the emission of electron from the surface of a hot filament or a hot meta.

32:27 All right, we're going to take a question from this.

32:31 We have the first question, which is two cells.

32:34 Let's say the first question, the first question.

32:44 Two cells, each of EMF, four votes, two cells, we have these, two cells, two cells, which is this, four votes, four votes.

33:08 And internal resistance of 0.5, internal resistance of 0.5, internal resistance of 0.5 are connected in series.

33:22 They are made to supply a current of a combination of three resistors. One of the resistance, four ohms, four ohms, connected in series, four ohms, four ohms, connected in series to a parallel combination of two other resistance

33:52 of five ohms. That is, we have it to be like this, we have five ohms, we have five ohms, we have five ohms.

34:15 Now, the question says draw the second diagram. Now, this, the second diagram, which is A, B is calculate the current in the circuits.

34:27 Now, for which to calculate the circuits, the current in the circuits, the first we have to get here, this is the parallel, this is the EMF and this are the internal resistors.

34:39 Now, let's get the fourth one, which is in parallel, that is, five is parallel to five. That simply means what?

34:50 Arru equivalence is equal towards Arru 1, Arru 2 over Arru 1 plus Arru 2, which is equal towards five times five over five plus five.

35:14 Which will give us 25 over 10, which will give us 2.5 ohms. That is, in the parallel form, we have what? Arru equivalence is equal to 2.5 ohms.

35:41 Now, from there, let's get the, in cities, in cities, we have here, like this, to be 2.5. So, in cities, we have four ohms plus 2.5 ohms, which will give us six points, five ohms.

36:09 Now, let's get the internal resistors, internal resistors, internal resistors, which will give us 0.5 plus 0.5, will give us 1.0 ohms.

36:32 Now, let's get the total voltage, total voltage, total voltage will give us V1 plus V2.

36:53 We have results V2 is equal to 4 plus 4, will give us each voltage. Now, we can get the current from this now to see that V is equal to I into brackets, internal resistance plus the SNR resistance.

37:15 Now, what is our voltage? Our voltage is what's 8 volts is equal to the current which we don't know, open a brackets.

37:29 Now, our internal resistance, which is 1 plus our SNR resistance, which is 6.5, then we have 8 is equal to this is equal to this plus this will give us 7.5.

37:48 Then, we can divide this by 7.5, 7.5. This can take care of this, we have the current is equal.

38:08 Now, let's use our calculator, let's use our calculator.

38:21 Now, we have 8 divided by 7.5, will give us 1.066. So, let's approximate towards 1.07 ampere.

38:46 So, the current is equal to 1.07 ampere. Does the first question? Now, the second question is, the PD across the parallel combination.

39:02 Now, across the parallel combination, we have that, let's go up to check our parallel combination.

39:20 We have it as 2.5, 2.5, in parallel combination, 2.5. So, we have the same, we have V, V is equal to I, R, in parallel combination.

39:42 And that is for C. Now, what is the potential difference? We don't know, what's the current?

39:50 The current is the total current that flows through the circuits. We have 1.07 times the resistor, which is 2.5.

40:00 In the parallel pleats, 2.5, in the parallel pleats, we have V. Ok, let's use our calculator.

40:14 From the calculator, we have 1.07 times 2.5. And that will give us what? 2.675V.

40:42 Now, that is the potential difference across the parallel combination. The D part, the question says, couple it in loss voltage of the battery.

40:55 Now, how can we get the loss voltage? The loss voltage minus V is equals to I, R, which is the internal resistance of the cell.

41:05 We have E minus V, which is equals to the internal resistance of the cell. The current is 1.07 times.

41:17 Now, let's go up to check for the internal resistance of the cell.

41:25 The internal resistance of the cell, we have got 1.01, 1.01 times 1.01.

41:43 And we multiply it, we have got E minus V is equals to 1.01 times. Now, we have got us as votes.

41:58 We have got to take this one as an evolution. Thank you for watching with us. I am M N N D John. See you in the next class.