A loop of wire enclosing an area `S` is placed in a region where the magnetic field is perpendicular to the plane. The magnetic field `B` varies with time according to the expression `B=B_0e^(-at)` where a is some constant. That is, at `t= 0`. The field is `B_0` and for `t gt 0`, the field decreases exponentially. Find the induced emf in the loop as a function of time.

Answer

A, B

Explanation

`phi=BS=B_2Se^(-at)`
induced emf`=|(dphi)/(dt)|=aB_0Se^(-at)`