Question

A square loop of copper wire is initially placed perpendicular to the lines of a constant magnetic field of 5 x 10^-3 tesla. The area enclosed by the loop is 0.2 square meter. The loop is then turned through an angle of 90° so that the plane of the loop is parallel to the field lines. The turn takes 0.1 second. The average emf induced in the loop during the turn is

(A) 1.0 x 10^-4 V 

(B) 2.5 x 10^-3 V 

(C) 0.01 V 

(D) 100 V 

(E) 400 V

Answer 1

The correct option is: (E) 400 V

Explanation:

As long as the flux inside the loop is changing, there will be an induced current. Since choice E has both objects moving in the same direction, the flux through the loop remains constant so no need to induce a current.