Example 10.5 A simple AC generator is made by inserting a loop of radius d ¼ 50 mm inside a long solenoid of
radius b ¼ 60 mm. The number of turns per unit length of the solenoid is n ¼ 1,000 turns/m and these carry a DC
current I ¼ 1 A. The loop is connected to the outside and is provided with an axis to rotate, as shown in Figure 10.10:
(a) If the loop rotates at 3,000 rpm, calculate the emf in the loop.
(b) If the loop is made of copper wire, and the wire has a diameter D ¼ 1 mm, calculate the maximum current the loop
can supply (shorted output). Neglect resistance of wires leading to the loop. The conductivity of copper is
5.7 107 S/m.
(c) How much energy must be expended in rotating the loop in one hour if the terminals of the loop are shorted?