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. `4piBt(R_0+t^2)` clockwise

Answer

C

Explanation

`e=-(dphi)/(dt)=piBd/(dt)(R^2)`