Kirchhoff's Current Law - states that the current entering a...

Kirchhoff's Current Law - states that the current entering a point in a circuit is equal to the summation of the currents exiting. Kirchhoff's Voltage Law - states that the summation of all voltage drops in a closed loop must equal to zero which is a result of the electrostatic field being conservative. (Conventional) current flowing through the cell has a positive voltage (gains energy). Current going through a resistor has a negative voltage (loses energy). Find all the currents and voltages across each resistor and cell in the following circuits; 12V 4? 5V 3? 2?

Transcript

00:01 Here given that three resistance as r1 is equal to 1000 om, r2 is equals to 500 om and r3 is equal to 1500 om.

00:20 First for a part we have to calculate the resistance.

00:26 What is the total resistance when here v is equal to 10 volt? so we will apply the formula because there are resistance in series combination first.

00:39 So r is equal to in series combination, r is equal to r1 plus r2 plus r3, so here, thousand plus 500 plus 1, plus 1 ,500, ome is equal to 3, 3 ,000, plus 1 ,500, 3000 ome that is total resistance will be this.

01:13 Now we know that we first part a is the total resistance now for b part we have to calculate i so we know that since v is equal to ir so i is equal to v divided by r now v is 10 and r is 3 ,000 so here current is 0 .003 as a part, resistance was and current is here, current is 0 .003 ampere, same as for resistance here, 3 ,000 home.

02:21 And for c part, they have asked about.

02:23 The part of first question, we have asked if the resistance is increases in series.

02:28 Since we know that b is equal to ir and i is equal to b divided by r.

02:38 If r is increasing, so i will be decreasing in series.

03:04 For now, second question, if r, again there are c registers are in parallel.

03:10 And the resistance value same, 1 ,000 ome, 500 ome and 1500 ome.

03:24 And here v is equal to 10 volt because it is a parallel combination.

03:31 So for parallel combination 1 upon r is equal to 1 upon r1, that means 1 divided by r1 plus 1 divided by r2 plus 1 divided by r3.

03:50 So we put the value 1 divided by 1000 plus 1 divided by 500 plus 1 divided by 1500.

04:00 Here we can take as lc and that is 3 ,000.

04:04 So here it will be coming 1 ,000 table 3 times, 500 tables 6 times and here it will be 2 times.

04:15 So total will be 10 divided by 3000.

04:19 This is the value for 1 divided by r.

04:22 And we have to calculate r.

04:24 We will do because 1 divided by r is equal to 10 divided by 3 ,000...

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