In a closed loop, which has some inductance but negligible resistance, uniform but time varying magentic field is applied directed into the plane of the loop. Variation of field with time is shown in Fig. Initially current in loop was zero. Then .

Options

A. emf induced in the loop is zero at `t = 2 s`
B. current in the loop will be maximum at `t = 2 s`
C. direciton of emf in the loop will not change at `t = 2 s`
D. none of above

Answer

A

Explanation

As `phi = BA` and `|e| = (d phi)/(dt)`,
therefore, from Fig. we find that at
`t = 2 s, B = max, phi = max , e = 0`.
The flux increases from 0 to 2 sec and it decreases from `t = 2 s` to `t = 4s`.
Therefore, the direction of e.m.f. in the loop is reversed at `t = 2 s`.
Choice (a) is correct.