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

• A. $40 \, \Omega$
• B. $25\, \Omega$
• C. $250 \, \Omega$
• D. $500\, \Omega$

Answer 1

Answer: (C)

Current sensitivity, $\frac{\theta}{i}=\frac{5}{10^{-3}}=5000 \frac{ div }{ A } \cdots$ (i)
Voltage sensitivity, $\frac{\theta}{V}=20 \frac{\operatorname{div}}{ V }$ ........ (ii)
(i) $/( ii )$, we get $\frac{\theta / i}{\theta / V}=\frac{5000}{10}=250$
$\Rightarrow \frac{V}{i}=R=250\, \Omega$