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AP® Physics 1 & 2

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Magnetic Domains: Bar Magnet Analysis

APPH12-KZXD9J

A student is asked to use the representation of magnetic domains to explain how an iron bar magnet maintains a permanent magnetic field. As shown in the diagram, the north pole of the bar magnet lies to the left and the south pole to the right.

Which statement below is the best explanation of the magnetic domains within the bar magnet?

A

The bar magnet has lots of north magnetic domains near the north pole, and an equal number of south magnetic domains near the south pole. The middle of the bar magnet is relatively free of magnetic domains.

B

There are exactly two magnetic domains in the bar magnet, one for the north pole and one for the south pole.

C

The bar magnet contains numerous microscopic domains spread equally throughout. Each domain is aligned with its north pole to the left and its south pole to the right.

D

Magnetic domains only arise from moving charges. There are no moving charges in the bar magnet, so one cannot explain this magnetism using magnetic domains.