In equal-arm balances from the early twentieth century, it is sometimes observed that an aluminum sheet hangs from one of the ar
ms and passes between the poles of a magnet. This causes the oscillations of the equal-arm balance to decay rapidly. In the absence of such magnetic braking, the oscillation might continue for a very long time, so that the experimenter would have to wait to take a reading. The oscillations decay because which of the following reasons? A. Aluminum is paramagnetic. B. Currents in the aluminum sheet set up a magnetic field that opposes the oscillations. C. The aluminum sheet is attracted to the magnet.
Currents in the aluminum sheet set up a magnetic field that opposes the oscillations
Explanation:
It has been stated in the question that the aluminum sheet hangs from one of the arms and passes between the poles of the magnet and causes the magnetic field to decay rapidly. In the absence of this magnetic breaking, the oscillation may continue for a long time.
As the aluminum hangs from one of the sheets and passes between the poles of the magnet, the magnetic flux linked to the sheet changes and emf is induced in the sheet according to Lenz law. As a result of this induced emf, eddy currents are developed on the plate. The Eddy currents opposes the magnetic force on the aluminum sheets. This opposes the oscillation of the aluminum sheet and causes it to come to rest.
