1. The problem statement, all variables and given/known data A rectangular coil of 200 turns has a length of 200 mm and width 120 mm. The coil rotates with a constant angular speed of 1200 revolutions per minute about an axis through the midpoints of its longer sides in a uniform magnetic field of 2.4 x 10-2 T. Starting from a time when the coil’s plane is parallel to the magnetic field, calculate the average induced electromotive force whilst the coil is turning 1/(2pi) radians. 2. Relevant equations E(emf) = N x B x w x A x sin (theta) where N = number of turns B = magnetic field (T) A = area of coil w = angular velocity (rad/s) theta = angle made by coil wrt perpendicular to the field 3. The attempt at a solution Angular velocity = 40pi (1200rpm) As the coil rotates through the field plane the induced emf is at the maximum (sin (theta) = 1) where E = 200 x 2.4 x 10-2 T x 40pi x 0.120m x 0.200m x sin (pi/2) = 14.47V After rotating towards the vertical through the rather small angle 1/(2pi) radians: E = 200 x 2.4 x 10-2T x 40pi x .120m x .200m x sin (pi/2 - (1/(2pi)) = 14.29V The given result is 9.216V so I've obviously missed something. Yet - it seems unusual that after rotating through such a small angle that the induced voltage should fall as low as the given answer. Help gratefully received!