The machine of Problem 12.1.4 can be used as a motor. Let the terminals of the coil be connected to a voltage source of 1 kV rms. If the motor runs at 1800 r/min and draws a current of 2 A, find the torque supplied to the mechanical load.
Problem 12.1.4
A coil is formed by connecting 15 conducting loops, or turns, in series. Each loop has length l = 2.5 m and width w = 10 cm. The 15-turn coil is rotated at a constant speed of 30 r/s (or 1800 r/min) in a magnetic field of density B = 2 T. The configuration of
Figure P12.1.3 applies.
(a) Find the induced emf across the coil.
(b) Determine the average power delivered to the resistor R = 500 Ω, which is connected between the terminals of the coil.
(c) Calculate the average mechanical torque needed to turn the coil and generate power for the resistor. Identify the action of the device as that of a motor or a generator.
