Question

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

• A.
• B.
• C.
• D.

Answer 1

Answer: (A)

We know induced induced emf $e=-L\frac{di}{dt}$
During 0 to $\frac{T}{4},\frac{di}{dt}=$ constant
so, induced emf $e=-ve$
for $\frac{T}{4}$ to $\frac{T}{2},\frac{di}{dt}=0$
induced emf $e=0$
For $\frac{T}{2}$ to $\frac{3T}{4},\frac{di}{dt}=$ constant
sol induced emf $e=+ve$