College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 71

An 820-turn wire coil of resistance 24.0 V is placed on top of a 12 500-turn, 7.00-cm-long solenoid, as in Figure P20.57. Both coil and solenoid have crosssectional areas of 1.00 × 10 4 m 2. (a) How long does it take the solenoid current to reach 0.632 times its maximum value (b) Determine the average back emf caused by the self-inductance of the solenoid during this interval. The magnetic field produced by the solenoid at the location of the coil is one-half as strong as the field at the center of the solenoid. (c) Determine the average rate of change in magnetic flux through each turn of the coil during the stated interval. (d) Find the magnitude of the average induced current in the coil.