Q. If 100 kWh of energy is consumed at 66 V in a copper voltmeter, then the mass of copper liberated will be (Given ,ECE of $Cu = 0.33 \times 10^{- 6}kg\ C^{- 1})$
A) 1.65 kg
B) 1.8 kg
C) 3.3 kg
D) 3.6 kg
Explanation
(b) Energy, $E = 1\ kWh = 3.6 \times 10^{6}\ J = QV$
or $\ Q = E/V$
$m = zQ = z\frac{E}{V}$
$\ = \frac{\left( 0.33 \times 10^{- 6} \right)(3.6 \times 10^{6})}{66} = 1.8$ kg.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.