Find out the following if A is connected with C and B is connected with D.
(i) How much charge flows in the circuit.
(ii) How much heat is produced in the circuit.

Explanation

Let potential of B and D is zero and common potential on capacitors is V, then at A and C it will be V. By charge conservation.
` 3V+2V= 40+30`
` (##MOT_CON_JEE_PHY_C25_SLV_006_S01.png" width="80%">
` 5V =70 " "rArr " " V =14` volt
Charge flow `= 40 -28 =12 mu C `
Now final charges on each plate is shown in the figure
` (##MOT_CON_JEE_PHY_C25_SLV_006_S02.png" width="80%">
(ii) Heat produced ` = ( 1)/(2) xx 2 xx (20 )^(2) +(1)/(2) xx 3 xx (10 ) ^(2) `
`- (1)/(2) xx 5 xx( 14)^(2) = 400 +150 - 490`
= ` 550 - 490= 60 muJ `
• When capacitor plates are joined then the charge remains conserved. • We can also use direct formula of redistribution as given above.