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 ______.

Options

• 10⁵

• 10³

• 9995

• 99995

Answer 1

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 9995.

Explanation:

Resistance of Galvanometer,

G = `"Current sensitivity"/"Voltage sensitivity"` ⇒ G = `10/2` = 50 Ω

Here i_g = Full scale deflection current = `150/10` = 15 mA

V = voltage to be measured = 150 volts

(such that each division reads 1 volt)

⇒ R = `150/(15xx10^-3)-5`

= 9995Ω