A coil of area 10   m 2 is placed in a uniform magnetic field of 0 . 3 k lb. m - 2 , with its plane perpendicular to the field. The coil rotates at a uniform rate to complete the revolution in 8   s . find the average emf in   mV . in the coil during intervals when the coil rotates from i. 0 ° to 90 ° position ii. 90 ° to 180 ° position ii. 180 ° to 270 ° position iv. 270

Step-by-step solution

Magnetic flux is given by ϕ = B A cos θ e = - ∆ ϕ ∆ t = - ϕ 2 - ϕ 1 t 2 - t 1 case i : for 0 °   to   90 ° position e = - B A cos 90 - B A cos 0 t 2 - t 1 = 0 . 3 × 10 2 = 3 2 mV case ii : for 90 °   to   180 ° position e = - B A cos 180 - B A cos 90 t 2 - t 1 = 0 . 3 × 10 2 = 3 2 mV case iii : for 180 °   to   270 ° position e = - B A cos 270 - B A cos 180 t 2 - t 1 = - 0 . 3 × 10 2 = - 3 2 mV case iv :