An ammeter of resistance ' R ' gives a full scale deflection when a current of 2 A passes through it. If it is to be converted into an ammeter to measure maximum current of 10 ~A , the required shunt is

Step-by-step solution

Consider the diagram below: Given, i _ g =2 ~A is current for maximum deflection, R = R _ g is the resistance of galvanometer, I =10 ~A is the maximum current to be measured by the ammeter. On considering same potential drop across the galvanometer and the shunt resistance: (I-i_g ) S=i_g R . On plugging in the given values, (10 A-2 A) S=(2 A) R The shunt resistance S can be written as: S= R 4