Question

How can we convert a galvanometer into an ammeter of given range?

Answer 1

Solution -

A galvanometer can detect only small currents. Thus, to measure large currents it is converted into an ammeter. It can be converted into an ammeter by connecting a low resistance called shunt resistance in parallel to the galvanometer.

Let G be the resistance of the galvanometer and Ig be the current for full scale deflection in the galvanometer, the value of the shunt resistance required to convert the galvanometer into an ammeter of 0 to I ampere is,

S = (Ig*G)/(I-Ig)

Ig is calculated using the equation, Ig = nk, where n is the number of divisions on the galvanometer and k is the figure of merit of galvanometer.