Question

14- please help me with my physics HW

Wire is wound on a square frame, 30 cm by 30 cm, to form a coil of 7 turns. The frame is mounted on a horizontal shaft through its centre (perpendicular to the plane of the diagram), as shown in the figure. The coil is in clockwise rotation, with a period of 0.060 s. A uniform, horizontal, magnetic field of magnitude 0.40 T is present. At a given instant, the plane of the coil forms a 60 degrees angle with the horizontal, as shown. At that instant, what is the magnitude of the emf induced in the coil? 23 V 13 V 2.1 V 26 V 3.6 V the power

Answer 1

e = N d(phi)/dt

here theta is angle between B vector and area vector (area vector is perpendicular to the plane of coil)

phi = B.A cos theta = .40 x (.3 x .3) x cos (30) = 0.036 x .866 = 0.031176

e = (7 x 0.031176) / (.060)

e = 3.6 V (answer E)