Question

with this type of electric motor, the rotor is made from very powerful rare earth permanent magnet alloys, typically neodymium - iron - boron or samarium - cobalt.

a. multiphase
b. permanent magnet
c. brushless
d. synchronous

Explanation:

The key description in the text is about the rotor being made from powerful rare - earth permanent magnet alloys. This directly relates to the characteristics of a permanent magnet electric motor. A multiphasemotor is mainly about the number of phases in the electrical supply. A brushless motor emphasizes the absence of brushes (though some brushless motors can have permanent magnets, the text's focus is on the magnet material). A synchronous motor is about the speed relationship with the supply frequency.

Answer:

B. Permanent magnet