A square coil of wire of side 3.95 cm is placed in a uniform magnetic field of magnitude 2.25 T directed into the page as in the figure shown below. The coil has 34.0 turns and a resistance of 0.780 Ω. If the coil is rotated through an angle of 90.0° about the horizontal axis shown in 0.335 s, find the following. (a) the magnitude of the average emf induced in the coil during this rotation mV (b) the average current induced in the coil during this rotation mA

In this case we shall calculate rate of change of flux in the coli to calculate induced emf.

Flux through the coil = no of turns x area x magnetic field perpendicular to it

=34 x 2.25 x (3.95) ²x 10⁻⁴ Weber

= 1193.4 x 10⁻⁴Weber

Final flux through the coil after turn by 90°

= 1193.4 x 10⁻⁴ cos 90 ° = 0

Change of flux

= 1193.4 x 10⁻⁴ weber.

Time taken = 0.335 s.

Average emf = Rate of change of flux

= change in flux / time

=1193.4 x 10⁻⁴ /.335

= 3562.4 x 10⁻⁴

356.24 x 10⁻³

=356.24 mV.

Current induced = emf induced / resistance

= 356.24/.780

= 456.71 mA.