A coil has 1000 turns and 500 ~cm ^2 as its area. The plane of the coil is placed at right angles to a magnetic induction field of 2 10⁻⁵ ~Wb / m ^2 . The coil is rotated through 180^ in 0.2 ~s . The average emf induced in the coil, in mV , is

Step-by-step solution

N=1000, A=500 ~cm ^2=500 10⁻⁴=5 10⁻² ~m ^2B=2 10⁻⁵ ~Wb / m ^2, ₁=0^ , ₂=180^ , t=0.2 ~s Initial flux linked with coil, ₁=N B A ₁=N B A 0^ =N B A Final flux, ₂=N B A 180^ =N B A(-1)=-N B A Change in flux, = ₂- ₁=-N B A-(N B A)=-2 N B A Induced emf, e= - t =- (-2 N B A) t = 2 N B A t = 2 1000 2 10⁻⁵ 5 10⁻² 0.2 =10 10⁻³ ~V =10 mV