Two capacitors one that has a capacitance of 400 mf and one...

Two capacitors, one that has a capacitance of 4.00 mF and one that has a capacitance of 12.0 mF, are connected in parallel. The parallel combination is then connected across the terminals of a 12.0-V battery. Next, they are carefully disconnected so that they are not discharged. They are then reconnected to each other - the positive plate of each capacitor connected to the negative plate of the other. (a) Find the potential difference across each capacitor after they are reconnected. V4 = .... kV (b) Find the energy stored in the capacitors before they are disconnected from the battery. V12 = ..... kV (c) Find the energy stored after they are reconnected. Energy = ..... in microjoules

Transcript

00:01 There is a capacitor c1 is equal to 4 millifera and c2 is equal to 12 millifera.

00:13 They are connected in parallel to a battery of 12 volt.

00:18 It means c1 and c2 they are connected in parallel to a battery of 12 volt.

00:33 So when we do this, the charge is stored on the, means plates of c1 and c2.

00:43 The potential of c1 and c2 is equal to 12 volt because they are in parallel.

00:48 But the charge is different.

00:50 Charge on the plate of c1, q1 is equal to c1 into v.

00:56 C1 is 4mmel ferr, 4 into 10 to minus 3 ferr into 12.

01:02 It means 48 into 10 days to minus 3 kula.

01:07 Similarly, charge on the plate of c2, qa, u2 is equal to c2 into v, c2 is 12 milliferaat into 12 volt.

01:18 It means it is 144 into 10 rise to minus 3, cool up.

01:25 Right.

01:26 Now they are carefully disconnected from the battery and we are reconnected again with the positive plate of c1 is connected with the negative plate of c2.

01:45 It means we have removed them without discharging them.

01:52 This means what we remove c1 first.

01:55 We do not remove the battery.

01:57 We remove c1 first, then we remove c2, then we connect c1 and c2 in parallel with the reverse polarity.

02:08 If we remove battery first, then charge will flow between c1 and c2 and their equilibrium will change so the word they are carefully removed means the battery is not removed first c1 is removed first then c2 is removed then they are connected so when we remove c1 c1 is removed with his full charge because it has nothing to discharge when we remove c2 it is still connected to battery so it it maintained its full charge so now c1 and c2 are connected in opposite polarity.

02:49 It means they are connected in this way that this is suppose c1, its positive, is connected to the means negative.

03:03 This is c2 and its positive is connected to the minus negative.

03:08 So this is c1 and here charge is q1.

03:13 This is c2.

03:14 Here charges, same is q2.

03:15 So q1 is equal to 48 into 10 rest to minus 3 coulum and q2 is equal to 144 into 10 rest to minus 3 coulum.

03:29 Now if we connect like this, the charge flows from higher value to the low, say means lower value.

03:37 And it does not, you know, come to a equilibrium position, but that means we can say, out of the 144 into 10 to minus 3 is kulam of, say, me, c2, 48 into 10 to minus 3, it means coulum, is neutralized with q1, with c1, say, because this positive charge attracts the negative charge.

04:05 So as soon as we connect them, the net charge of the system is now only 144 minus 4, minus 48 into 10 raised to minus 3.

04:22 It means it is 96 into 10 to minus 3 kula.

04:30 This is a net charge of the system of q1 and q2...

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