A coil having an area `A_(0)` is placed in a magnetic field which changes from `B_(0)` to `4B_(0)` in a time interval `t`. The e.m.f. induced in the coil will be

Options

A. `3A_(0)B_(0)//t`
B. `4A_(0)B_(0)//t`
C. `3B_(0)//A_(0)t`
D. `4A_(0)//B_(0)t`

Answer

A

Explanation

Induced e.m.f. `epsilon =(d phi)/(dt)=(dBA)/(dt)=A_(0)(dB)/(dt)`
`=A_(0)((4B_(0)-B_(0))/(t))=3A_(0)B_(0)//t`