Question

A 10 $\mu$ F capacitor is charged by a battery of emf 200 V. The energy drawn from the battery, and the energy stored in the capacitor, are respectively

• A. 0.05 J and 0 mJ
• B. 0.05 mJ and 0.05 mJ
• C. 0.4 J and 0.2 J
• D. 1.0 mJ and 0.5 mJ

Answer 1

The correct option is C 0.4 J and 0.2 J

$C=10\mu F=10\times {10}^{-6}F,V=200V$
Energy stored $=\frac{1}{2}C{V}^2$
$=\frac{1}{2}\times 10\times {10}^{-6}\times 200\times 200$
$=2\times {10}^{-1}=0.2J$
Energy drawn from the battery $=C{V}^2=10\times {10}^{-6}\times (200{)}^2=0.4J$