PYQ NEET- Moving Charges And Magnetism L-5

Question: Current sensitivity of a moving coil galvanometer is $5 \mathrm{div} / \mathrm{mA}$ and its voltage sensitivity (angular deflection per unit voltage applied) is $20 \mathrm{div} / \mathrm{V}$. The resistance of the galvanometer is#

A) $40 \Omega$

B) $25 \Omega$

C) $250 \Omega$

D) $500 \Omega$

Answer: (C) $250 \Omega$#

Sol:#

Current sensitivity of moving coil galvanometer $$ \mathrm{I}_{\mathrm{S}}=\frac{N B A}{C} $$

Voltage sensitivity of moving coil galvanometer, $$ \mathrm{V}_{\mathrm{S}}=\frac{N B A}{C R_G} $$

Dividing eqn. (i) by (ii)

Resistance of galvanometer $$ \mathrm{R}_{\mathrm{G}}=\frac{I_s}{V_S}=\frac{5 \times 1}{20 \times 10^{-3}}=\frac{5000}{20}=250 \Omega $$