The current sensitivity of a moving-coil galvanometer is increased by 25% only by changing the number of turns and wire cross-section while keeping the coil resistance constant. The percentage change in voltage sensitivity is:
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Question

The current sensitivity of a moving-coil galvanometer is increased by 25% only by changing the number of turns and wire cross-section while keeping the coil resistance constant. The percentage change in voltage sensitivity is:

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G1 Physics · Accepted Answer

Current sensitivity Sᵢ = θ/I = NAB/k. Voltage sensitivity Sᵥ = θ/V = (θ/I)/R = Sᵢ/R. Since R is kept constant, a 25% increase in current sensitivity produces the same 25% increase in voltage sensitivity.