A light aluminum ring is suspended freely facing one end of a large electromagnet. When the steady c

Question

A light aluminum ring is suspended freely facing one end of a large electromagnet. When the steady current flowing in the electromagnet is suddenly switched off, the aluminum ring will:

Professor PC Thomas Classes · Answer

(b) : When the current in the electromagnet is switched off, the magnetic field rapidly collapses, causing a sharp decrease in the magnetic flux linked with the aluminum ring. By Lenz's law, an induced current will flow in the ring in a direction that tries to oppose this decrease. It does so by creating a magnetic field identical in polarity to the collapsing field, resulting in an attractive force that pulls the ring towards the electromagnet.