A coil of effective area `4m^(2)` is placed with its plane perpendicular to magnetic induction of 0.04 `Wb//m^(2)`. The induced emf in the coil if magnetic induction reduces to `(1//4)^(th)` of its original value in 0.5 s will be

Options

A. 0.5 V
B. 0.75 V
C. 0.4 V
D. 0.24 V

Answer

D

Explanation

`e=(dphi)/(dt)=(phi_(1)-phi_(2))/(dt)=(Acostheta[B_(1)-B_(2)])/(dt)`
`=(4xxcos0xx[0.04-0.01])/(0.5)`
`=0.24V`