question_answer

In figure is shown a system of four capacitors connected across a 10 V battery. Charge that will flow from switch S when it is closed is: [JEE Main Online Paper (Held On 11 April 2015)]  

A) \[5\mu C\] from b to a

B) \[20\mu C\] from a to b

C) \[5\mu C\] from a to b

D)  zero

Correct Answer: A

Solution :

for upper link \[{{C}_{eq}}=\frac{6}{5}\mu F\] \[\therefore \]\[{{\text{Q}}_{\text{upper}}}={{\text{Q}}_{\text{lower}}}=12\mu C\]on closing switch charge on \[2\mu F\]is \[10\mu C\And \]that on \[3\mu F\]is \[15\mu C\] \[\therefore \]\[{{q}_{i}}=-12+12=0\] \[\therefore \]\[{{q}_{j}}=15-10=5\mu C\] \[\therefore \] \[\]