Q. When a copper voltmeter is connected with a battery of emf 12V, 2 g of copper is deposited in 30 min. If the same voltmeter is connected across 6 V battery, the mass of copper deposited in 45 min would be
A) 1 g
B) 1.5 g
C) 2 g
D) 2.5 g
Explanation
(b) As $m = z\ l\ t = z\left( \ \frac{V}{R} \right)t\ \ ie,\ m \propto Vt$
$\therefore\ $ $\frac{m_{2}}{m_{1}} = \frac{V_{2}t_{2}}{V_{1}t_{1}}$
or ${\ m}_{2} = \frac{V_{2}t_{2}}{V_{1}t_{2}} \times m_{1} = \frac{6 \times 45 \times 2}{12 \times 30} =$1.5g.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.