A moving coil galvanometer has 100 equal divisions. Its current sensitivity is 20 divisions per mA and voltage sensitivity is 4 divisions per mV. To convert it into a voltmeter in which each division reads 1 V, the resistance needed to be connected in series with the coil will be:

19995 Ω

The correct answer is Option (2) → 19995 Ω

Full scale deflection current: $I_g = 5 \, \text{mA}$

Galvanometer resistance: $R_g = 5 \, \Omega$

Required full scale voltage: $100 \, \text{V}$

Total resistance needed: $R = \frac{100}{5 \times 10^{-3}} = 20000 \, \Omega$

Series resistance: $R_s = R - R_g = 20000 - 5 = 19995 \, \Omega$

Answer: $19995 \, \Omega$