The current I in a coil varies with time as shown in the fig. The variation of induced emf with time would be

Options

A.
B.
C.
D.

Answer

A

Explanation

`e=-L(di)/(dt)`
When, `0letle(T)/(4),(di)/(dt)` = constant, so e is negative and constant.
When, `(T)/(4)letle(T)/(2),(di)/(dt)=0`, so e = 0.
When, `(T)/(2)letle(3T)/(4),(di)/(dt)` = constant, so e is positive and constant.
When, `(3T)/(4)letleT,(di)/(dt)=0`, so e = 0.