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Question:

Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity (angular deflection per unit voltage applied) is 20 div/V. The resistance of the galvanometer is?

250Ω

25Ω

40Ω

500Ω

Solution:

Current sensitivity Ig = NBA/K = 5 div/mA = 5000 div/A
Voltage sensitivity Vs = NBA/KR = 20 div/V
⇒ Ig/Vs = R
⇒ R = 5000/20 = 250Ω
Option 1 is correct.