Question

In the figure the flux through the loop perpendicular to the plane of the coil and directed into the paper is varying according to the relation f = 6t² + 7t + 1 where f is in milliweber and t is in second. The magnitude of the emf induced in the loop at t = 2s and the direction of induce current through R are–

• A. 39 mV; right to left
• B. 39 mV; left to right
• C. 31 m V; right to left
• D. 1mV; left to right

Answer 1

Answer: (D)

1mV; left to right

Answer 2

|e| = $\frac{d\varphi}{dt}$= 12t + 7

At t = 2s, |e| = 12 × 2 +7 = 39 mV

from Lenz's law current in the loop will be anticlockwise.