Question

A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10-divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistance in ohms needed to be connected in series with the coil will be -
A. 99995
B. 9995
C. `10^(3)`
D. `10^(3)`

Answer 1

Correct Answer - B
(b) Voltage sensitivity `= ("Current sensitivity")/("Resistance of galvaonometer G")`
`G = (10)/(2) Omega`
Here `i_(g) =` Full scale deflection current `= (150)/(10) = 15 mA`.
`V =` Voltage to be measued `= 150 xx 1 = 150 V`.
Hence `R = (V)/(i_(g)) - G = (150)/(15 xx 10^(-3)) 5 = 99995 Omega`