# A moving coil galvanometer has a resistance of 4 ohms and gives full-scale deflection when carrying 30 milliamperes.

A moving coil galvanometer has a resistance of 4 ohms and gives full-scale deflection when carrying 30 milliamperes. The instruments can be used to measure 150 volts by connecting in series with the instrument a resistance of

### Right Answer is:

4996 ohms

#### SOLUTION

The resistance of the galvanometer R_{G} = 4Ω

Full-scale deflection Current I_{F} = 30 mA = 30 × 10^{−3}A

Voltmeter Range V = 150 V

Let a resistor of resistance R be connected in series with the galvanometer to convert it into a voltmeter. This resistance is given as:

**R = V/I _{F} **

= 150/30 × 10^{−3 }= **5000V**

Hence the value of resistance to be connected in series

R_{G }− R = 5000 − 4 = **4996Ω**