CBSE Class 12-science Answered

First find the resistance of the galvanometer using the given information. R = V/I = 50mV/1mA= 50 ohms.

Then it is to be changed into an ammeter of range 0-0.5A. If shunt resistance is S then

i_gR_g = (i-i_g)S  potential drop across galvanometer equals potential drop across shunt.

where i is the maximum current equal to 0.5A
i_g is the maximum current through the galvanometer which is 10mA

R_g is the resistance of the galvanometer which is 50 ohms

Then solve for S.

To change the galvanometer into a voltmeter of given range

use the equation

V = I_g(R_g+R_S)

using the values find required series resistance, R_s.