The current sensitivity of a moving coil galvanometer increases by $20 \%$ when its resistance is doubled. Calculate, by what factor does the voltage sensitivity change?
Medium
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(a)
$S_{i_1}=\frac{N i A B}{k i}=\frac{N A B}{k}$
$S_{i_2}=\frac{1.2 N A B}{k}$
$S_{v_1}=\frac{N A B}{k R}=\frac{S_{i_1}}{R}$
$S_{v_2}=\frac{S_{i_2}}{2 R}=\frac{1.2(N A B)}{k(2 R)}$
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