Question

A $4\, \mu F$ capacitor is charged to 400 V. If its plates are joined through a resistance of $2\,k \Omega$, then heat produced in the resistance is

• A. 0.64 J
• B. 1.28 J
• C. 0.16 J
• D. 0.32 J

Answer 1

Answer: (D)

0.32 J

Answer 2

Capacitance (C) $=4\, \mu F = 4\, \times\, 10^{-6}\, F ;$ Voltage (V) = 400 volts and resistance (R) $= 2\, k\Omega = 2 \times 10^{3}\, \Omega.$
Heat produced = Electrical energy stored $= \frac{1}{2} CV^2$
$=\frac{1}{2} \times (4 \times10^{-6}) \times (400)^2 = 0.32\, J.$