Q. A silver voltameter of resistance $2\ ohm$ and a $3\ ohm$ resistor are connected in series across a cell. If a resistance of $2\ ohm$ is connected in parallel with the voltameter, then the rate of deposition of silver
A) Decreases by 25%
B) Increases by 25%
C) Increases by 37.5%
D) Decreases by 37.5%
Explanation
(d) Initially current through the voltmeter $i_{1} = \frac{V}{(3 + 2)} = \frac{V}{5}$
Finally main current $i = \frac{V}{3 + 1} = \frac{V}{4}$
Hence current through voltameter $i_{2} = \frac{V}{8}$
$\because$ Rate of deposition $(R) = \frac{m}{t} = Zi \Rightarrow R \propto i$
$\therefore$ % drop in rate $= \frac{R_{2} - R_{1}}{R_{1}} \times 100 = \frac{i_{2} - i_{1}}{i_{1}} \times 100$
$= \frac{\left( \frac{V}{8} - \frac{V}{5} \right)}{\frac{V}{5}} \times 100 = - 37.5\%$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.