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^(5)`

Answer 1

Correct Answer - B
(b)Voltage sensitivity
`= ( "Current sensitivity")/( "Resistance of galvanometer G")`
`implies G = (10)/(2) = 5 Omega`
Here `i_(g) =` Full scale deflection current
`(150)/(10) 15 mA`.
`V = ` voltage to be measured `= 150 xx 1 = 150 V`.
Hence `R = (V)/(i_(g)) - G = (150)/(15 xx 10^(-3)) - 5 = 9995 Omega`