A conducting loop of radius `R` is present in a uniform magnetic field `B` perpendicular to the plane of ring. If radius `R` varies as a function of time `t` as `R = R_(0)+t^(2)`. The emf induced in the loop is

Options

A. `2piBt(R_(0)+t^(2))` Clockwise
B. `2piBt(R_(0)+t^(2))` Anticlockwise
C. `4piBt(R_(0)+t^(2))` Anticlockwise
D. `4 pi B t(R_(0)+t^(2))` Clockwise

Answer

C

Explanation

`e = -(d phi)/(dt) = pi B(d)/(dt)(R^(2))`