Question

how is an unmagnetized piece of iron different from the same piece of iron when it is magnetized?
multiple choice
a magnetized piece of iron has an internal electric current running from the south pole to the north pole.
magnetic domains are randomly oriented in unmagnetized iron, aligned in magnetized iron.
magnetized iron has north monopoles at one end and south monopoles at the other end.
a magnetized piece of iron has an internal electric current running from the north pole to the south pole.

Explanation:

According to the domain theory of magnetism, in an unmagnetized piece of iron, the magnetic domains (small regions with their own magnetic fields) are randomly oriented. So, their magnetic fields cancel each other out. In a magnetized piece of iron, the magnetic domains are aligned in the same direction, creating a net magnetic field.

Option A is incorrect because there is no internal electric current running from the south pole to the north pole in a magnetized piece of iron. Option C is incorrect because magnetic monopoles (single - pole magnets) have not been found in nature. Option D is incorrect for the same reason as option A (no such internal electric current).

Answer:

Magnetic domains are randomly oriented in unmagnetized iron, aligned in magnetized iron.