- #1
sgstudent
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Homework Statement
An iron core with a solenoid coiled around it is in a circuit with a switch and a dc current supply. In front of it, there is a iron ring tied to the ceiling such that it faces the solenoid without touching the circuit. When the switch is turned on what is observed and explain your answer.
Homework Equations
none.
The Attempt at a Solution
I sort of understand the first part:
The iron ring will be repelled away as when the switch is turned on, the magnetic field strength of the solenoid becomes stronger. This results in a change in magnetic flux linkage and by faraday's law there is an induced emf across the ring. Since the ring is a closed circuit, by lenz's law there is an induced current flowing to form an induced pole to repel the iron core.
However, when we consider what happens after the magnetic field of the solenoid becomes constant I'm unsure what happens. Once it reaches it's maximum strength, the ring would no longer experience a change in the magnetic flux linkage. So it should fall back to its original position right? But as it falls back it would experience a change in magnetic flux linkage as it would go into a stronger region (closer to the solenoid means stronger magnetic field) so would it be repelled again such that there will be a jerking motion?
I think that that would happen as it makes sense? Thanks for the help :-)