Question

A square loop of side 15 cm being moved towards right at a constant speed of 2 cm/s as shown in figure. The front edge enters the 50 cm wide magnetic field at t = 0. The value of induced emf in the loop at t = 10 s will be :

• A. 0.3 mV
• B. 4.5 mV
• C. zero
• D. 3 mV

Answer 1

Answer: (C)

zero

Answer 2

At $t = 10s$, the complete loop is already inside the magnetic field. Since the loop is entirely within the magnetic field, there is no change in the flux as the loop moves through the field. The rate of change of magnetic flux $\frac{d\Phi}{dt}$ is zero because the area of the loop inside the magnetic field remains constant.

Thus, the induced emf is:

$e = \frac{d\Phi}{dt} = 0.$