Question

A $20\mu F$ capacitor is charged to potential of $500V$ and is connected to another $10\mu F$ capacitor charged to $200V$ in parallel. The charging batteries are disconnected. The final potential across the combination is:

• A. $233.33V$
• B. $400V$
• C. $1200V$
• D. $600V$

Answer 1

The correct option is B $400V$

We know charge$=$capacity$\times$ voltage.

So final voltage $=\frac{Q_{net}}{C_{net}}$

$Q_{net}=Q_1+Q_2=C_1{V}_1+C_2{V}_2$

In parallel the $C_{net}=C_1+C_2=30\mu F$

So putting Corresponding Values we get final voltage as $400V$

Option B is correct.