Galvanometer to be used as DC voltmeter; what multiplier resistance is required to measure 50 V at full scale?

Question

if a galvanometer is to be used as a DC voltmeter, its internal resistance (Rg), is 30 ohms and its full scale deflection occurs with 1 mA of current (Ig), what multiplier resistance (Rm) is required to measure 50 V at full scale?

please include formula used.

Answer 1

Just use V = IR,  If you want 1mA at 50 Volts then you need a resistance of 50/.001 = 50000 Ohms   , the internal resistance of 30 Ohms could be subtracted from that value, but I would ignore it as it is much lower than the 50,000 Ohms.