The current `i` in a coil varies with time as shown in the figure. The variation of induced emf with time would be

Options

A.
B.
C.
D.

Answer

B

Explanation

`t=0` to `t+(T)/(4),(di)/(dt)=(I)/(T//4)=(4I)/(T)` ,
`e=-L(di)/(dt)=-L.(4I)/(T)`
`i=(T)/(4)` to `t=(T)/(2),(di)/(dt)=0,e=0`
`t=(T)/(2)` to `t=(3T)/(4),(de)/(dt)=-(I)/(T//4)=-(4I)/(T)` ,
`e=-(Ldi)/(dt)=L.(4I)/(T)`
`t=(3T)/(4)` to `T,(di)/(dt)=0,e=0`