A moving coil galvanometer has 28 turns and area of coil is 4 10⁻² ~m ² . If the magnetic field is 0.2 ~T , then to increase the sensitivity by 25 % without changing area and field, the number of turns should be changed to

Step-by-step solution

Clven, number of turns in moving coil Balvunometer, N₁=28 Initial sensitivity, =8 Final seusitivity, S_ f =S_ j +25 % of S_ j aligned &=S+25 % of S &=S+ S 4 = 5 S 4 aligned Since, sensitivity of moving eoil galvanometer is given as S= N A B K 5 S 4 S = N_ f 28 N_ f = 28 5 4 =35 [A, B and K are constant]