A sinusoidal voltage is generated by an 85 turn coil, of dimensions 20 cm by 16 cm. The coil is rotated at 3000 rev/min, with its longer sides parallel to the faces of a pair of poles. If the flux density produced by the poles is 0.5 T, calculate
(a) the amplitude of the generated emf,
(b) the frequency,
(c) the r.m.s. and average values.