Magnetic Fields - Multiple Choice Questions

Q1. A coil with 20 circular turns each of diameter 60 mm is placed in a uniform magnetic field of flux density 90 mT.

Initially the plane of the coil is perpendicular to the magnetic field lines as shown in Figure X.

The coil is rotated about a vertical axis by 90° in a time of 0.20 s so that its plane becomes parallel to the field lines as shown in Figure Y.

Assume that the rate of change of flux linkage remains constant.

What is the emf induced in the coil?