If an alumnium sheet is held between the poles of a large bar magnet, it requires some force to pull it out of the magnetic field even though Al is not ferromagnetic and does not touch the poles.
Why?
(I was thinking thatmovement of the metal in a magnetic field induces an emf in theopposite direction...Yes? No?)
2006-10-24 05:02:35 · 3 answers · asked by BugGurl 3 in Science & Mathematics ➔ Physics
When you move the aluminum in the magnetic field, a current is induced in the aluminum by the motion. Because aluminum is a good conductor of electricity, the current can be large. This current interacts with the magnetic field to retard the motion. You have probably noticed that moving an insulator in such a field does not result in a retarding force. The classic auto speedometer relies on this effect: a permanent magnet, attached to the axle, rotates inside an aluminum cup, which is attached to the indicator needle on the dial (and also a spring). The faster the magnet rotates, the stronger the force, and the farther the needle moves.
2006-10-24 05:09:29 · answer #1 · answered by Anonymous · 1⤊ 0⤋
I think u r right. This induced emf in opposite direction is known as eddy's current. this flows in a circular mannar & produces a high temperature.
2006-10-24 12:08:57 · answer #2 · answered by poornima_durairaj 2 · 1⤊ 0⤋
You are correct. This principle is used in electromagnetic braking.
2006-10-24 12:15:59 · answer #3 · answered by Frank N 7 · 1⤊ 0⤋