Induction: Electromagnet and Aluminium Ring

[Numbergeek99]

I need some help with this task, I am stuck.

1. Homework Statement
An aluminium ring is placed on top of an elctromagnet.

a. The electro magnet is connected to AC. What will happen with the aluminium ring? Motivate your answer.

b. What will happen with the ring if the electromagnet is connected to DC? Motivate your answer.

c. If one would hold the ring such that the aluminium ring has contact with the electro magnet would its temperature increase. Why?

Homework Equations

None, or at least I have not found one yet.

The Attempt at a Solution

My answers: [/B]
a. The electromagnetic force on the ring will change direction according to the frequency of the AC.

b. The ring would be attracted to the magnet.

c. The temperature of the ring would increase given that the electromagnetic force would be pointing away from the electromagnet.

The temperature would not increase if the electromagnetic force would be pointing in the opposite direction.

 

[scottdave]

Does it act the same in both situations? What are the properties of aluminum? What is the purpose of a ring vs other shapes? You may find Lenz's Law to be of some interest.