For a moving coil galvanometer, the deflection in the coil is 0 . 05 rad when a current of 10 mA is passed through it. If the torsional constant of suspension wire is 4 . 0 × 10 – 5 N m rad - 1 , the magnetic field is 0 . 01 T and the number of turns in the coil is 200 , the area of each turn (in cm 2 ) is :

Step-by-step solution

Given: θ = 0 . 05   rad ,   I = 10   mA ,   K = 4 × 10 - 5   N   m   rad - 1 ,   B = 0 . 01   T ,   N = 200 The torsional constant of a wire used in a moving coil galvanometer is given by K = N I A B θ , where, A is area of each turn So, A = K θ N I B = 4 × 10 - 5 × 0 . 05 200 × 10 × 10 - 3 × 0 . 01 Thus, A = 10 - 4   m 2 = 1   cm 2