Question

A battery does $200J$ of work in charging a capacitor. The energy stored in the capacitor is

• A. 200 J
• B. 100 J
• C. 50 J
• D. 400 J

Answer 1

Answer: (B)

$U=\frac{1}{2}C{v}^2$
$W=C{v}^2$
$U=\frac{W}{2}=100J$
(half of work is lost in heat)