Question

If the potential of a capacitor having capacity $6\mu F$ is increased from $10V$ to $20V$, then increase in its energy will be :

• A. $4\times {10}^{-4}J$
• B. $4\times {10}^{-6}J$
• C. $9\times {10}^{-4}J$
• D. $12\times {10}^{-6}J$

Answer 1

The correct option is C $9\times {10}^{-4}J$

Capacitance of capacitor (C) $=6\mu F=6\times {10}^{-6};$ Initial potential $\left(V_1\right)=10V$ and final potential $\left(V_2\right)=20V$.
The increase in energy $\Delta U=\frac{1}{2}C(V_2^2-V_1^2)$
$=\frac{1}{2}\times (6\times {10}^{-6})\times \left[\right(20{)}^2-\left(10{)}^2\right]$
$=(3\times {10}^{-6})\times 300=9\times {10}^{-4}J$