Question

A $1\mu F$ capacitor is charged to 200 V and then connected in parallel (+ve to +ve) with a $4\mu F$ capacitor charged to 100 V. The resultant potential difference is :

• A. 120 V
• B. 60 V
• C. 180 V
• D. 150 V

Answer 1

The correct option is A 120 V

Total charge of the system $=C_1{V}_1+C_2{V}_2=600\mu C$
Since the capacitors are connected in parallel , the potential across them should be the same. Let the charge across $1\mu F$ capacitor be $q\mu C$.
$q/1=(600-q)/4\Rightarrow 5q=600\Rightarrow q=120$
Potential across the capacitors $=Q/C=120V$