Alice builds an electric motor by positioning an electromagnet between the poles of a permanent magnet. When the electromagnet turns, the current through it switches direction because its connections to the voltage source are reversed. The repeated switching of the electromagnet's poles causes it to spin. This particular motor is used to turn the wheels of a toy car.

Question

Which of the following actions would increase the amount of force applied to the wheels of the toy car?
A.
decreasing the electric current running through the electromagnet
B.
decreasing the number of loops in the electromagnet's coil
C.
increasing the distance between the magnet's poles and the electromagnet
D.
replacing the magnet with a stronger magnet

Answer 1

To increase the amount of force applied to the wheels of the toy car, the best option among the provided choices is:

D. replacing the magnet with a stronger magnet.

Here's why the other options would not increase the force:

• A. decreasing the electric current running through the electromagnet: Decreasing the current would reduce the strength of the magnetic field generated by the electromagnet, thereby decreasing the force exerted by the motor.

• B. decreasing the number of loops in the electromagnet's coil: Fewer loops means a weaker magnetic field for a given current. This would also reduce the force produced by the electromagnet.

• C. increasing the distance between the magnet's poles and the electromagnet: Increasing the distance reduces the strength of the magnetic interaction between the electromagnet and the permanent magnet, which would decrease the force.

Therefore, replacing the magnet with a stronger magnet (D) would lead to a stronger magnetic field and increase the overall force exerted on the wheels of the toy car.