How does an electric motor use magnetic force to produce motion? The north pole of a permanent magnet placed in the center of an electromagnet attracts the north pole of the electromagnet.
The north pole of an electromagnet placed in the center of a permanent magnet attracts the north pole of the permanent magnet.
The north pole of a permanent magnet placed in the center of an electromagnet repels the north pole of the electromagnet.
The north pole of an electromagnet placed in the center of a permanent magnet repels the north pole of the permanent magnet.

The north pole of an electromagnet placed in the center of a permanent magnet repels the north pole of the permanent magnet.

Explanation:

The commutator of the electric motor reverses the current in each half revolution to keep the torque, turning the coil in the same direction. This occurs as the north pole of the electromagnet nears the south pole of the permanent magnet, and the current reverses, which causes the poles of the magnets to repel.

Thus, the correct answer is "the north pole of an electromagnet placed in the center of a permanent magnet repels the north pole of the permanent magnet".

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.