Question

In a galvanometer, when the number of turns $N$ becomes $2N$ and resistance $R$ becomes doubled, then

• A. Current sensitivity remains unchanged and voltage sensitivity doubles.
• B. Current sensitivity and voltage sensitivity remain unchanged.
• C. Current sensitivity doubles and voltage sensitivity remains unchanged.
• D. Current sensitivity and voltage sensitivity doubles.

Hint:

Voltage sensitivity = $\dfrac{\text{Current Sensitivity}}{Resistance}$. If both $N$ and $R$ double, only current sensitivity is affected.

Answer 1

The Correct Option is C

Current sensitivity $S_I \propto N$, so if $N$ doubles, $S_I$ also doubles.
Voltage sensitivity $S_V = \dfrac{S_I}{R}$, since both $N$ and $R$ double, the effect cancels: $S_V$ remains unchanged.
Therefore, current sensitivity doubles, voltage sensitivity remains the same.