Chapter 7 Electrodynamics Example 7.6. The \"jumping ring\" demonstration. If yo
ID: 1542955 • Letter: C
Question
Chapter 7 Electrodynamics Example 7.6. The "jumping ring" demonstration. If you wind a solenoidal coil around an iron core (the iron is there to beef up the magnetic field), place a metal ring on top, and plug it in, the ring will jump several feet in the air (Fig. 7.24). Why? Beceu the reet go up becauue loop ring the t solenoid but not FIGURE 7.24 Solution Before you turned on the current, the flux through the ring was zero. Afterward flux appeared (upward, in the diagram), and the generated in the ring to a emf a direction current (in ring) which, according to Lenz's lavM was in such that field tended to cancel this flux. This means that the current in the loop opposie the current in the solenoid. And opposite currents repel, so the ring long solenoid, of ratExplanation / Answer
According to Lenz's law emf is induced in the ring opposing its own cause that is flux from the solenoid so current is produced in the opposite direction in the ring and then due to repulsion between opposite currents the ring jumps.