Question

question 19 of 20
what allows the electromagnet in a motor to rotate consistently in one direction, transforming electrical energy into mechanical energy?
a. the permanent magnets turn their magnetic fields on and off.
b. the direction of the current in the metal loop frequently reverses.
c. the battery releases electrical energy in bursts of power.
d. the commutator acts as a crank for the metal loop.

Explanation:

In an electric - motor, a commutator changes the direction of current in the armature coil at regular intervals. This change in current direction ensures that the electromagnetic forces acting on the coil keep it rotating in one direction, thus converting electrical energy into mechanical energy. Permanent magnets do not turn their magnetic fields on and off in a typical motor operation. The battery provides a continuous or pulsed (in some cases) supply but its pulsing is not what makes the motor rotate in one direction. The commutator is not a physical crank for the metal loop.

Answer:

B. The direction of the current in the metal loop frequently reverses.