Question

In the circuit diagram given below, the value of the potential difference across the plates of the capacitors are:

• A. $17.5kV,7.5kV$
• B. $10kV,15kV$
• C. $5kV,20kV$
• D. $16.5kV,8.5kV$

Answer 1

The correct option is A $17.5kV,7.5kV$

Charge on both capacitors must be same as they are in series.
applying $KVL$
$\Rightarrow -13\times {10}^3+\frac{Q}{7\times {10}^{-6}}=0$
$\Rightarrow \frac{Q}{{10}^{-6}}\left(\frac{10}{21}\right)=25\times {10}^3$
$\Rightarrow Q=\frac{21\times 25\times {10}^2\times {10}^{-6}}{10}$
V accrors $3\mu F=\frac{21\times 25\times {10}^{-4}}{3\times {10}^{-6}}=17.5\times {10}^{3}V$
V accross $7\mu F=\frac{21\times 25\times {10}^{-4}}{7\times {10}^{-6}}=7.5\times {10}^{3}V$