Chapter 21, Problem 13P

You have the apparatus shown in Figure P21.13. A circular metal plate swings past the north pole of a permanent magnet. The metal consists of a series of rings of increasing radius Indicate the direction of the current in one ring (a) as the metal swings down from the left into the magnetic field and (b) as the metal swings up toward the ring out of the magnetic field Use Lenz's law to justify your answers.