A coil of area `A` lies in a uniform magnetic field `B` with its plane perpendicular to the field. In this position the normal to the coil makes an angle `0^(@)` with a field. The coil rotates at a uniform rate about its diameter to complete one rotation in time `T`. Find the average induced e.m.f. in the coil during the interval when coil rotates from:
(a) `0^(@)` to `90^(@)`
(b) `90^(@)` to `180^(@)`
(c) `180^(@)` to `270^(@)`
(d) `270^(@)` to `360^(@)`