Crash Course Physics: Magnetic Flux and Induction Quiz

What was the key discovery made by Joseph Henry and Michael Faraday regarding magnetic fields?

• Magnetic fields can create electric currents.

• Electric currents can create magnetic fields.

• Magnetic fields are constant over time.

• Electric currents cannot be induced by magnetic fields.

According to Faraday's Law of Induction, what induces an electromotive force (emf) in a loop of wire?

• A stationary electric charge

• A changing magnetic field

• A constant electric current

• A constant magnetic field

Which of the following factors does NOT affect the magnetic flux through a loop of wire?

• Strength of the magnetic field

• Area of the loop

• Angle between the magnetic field and the loop

• Length of the wire

How is the total emf in a coil of wire calculated?

• By adding the emf of each loop

• By multiplying the emf of one loop by the number of loops

• By dividing the emf of one loop by the number of loops

• By subtracting the emf of each loop

What does Lenz's Law state about the direction of the magnetic field generated by the induced current?

• It is in the opposite direction to the change in magnetic flux.

• It is in the same direction as the change in magnetic flux.

• It is parallel to the change in magnetic flux.

• It is perpendicular to the change in magnetic flux.

In the first scenario with the bar magnet, what is the direction of the current when the north pole is moved closer to the loop?

• Upward

• Clockwise

• Counterclockwise

• Downward

How does a hard drive use magnetic fields to read information?

• By using a constant magnetic field

• By rotating sections of the disk past a small electromagnet

• By magnetizing the entire disk

• By inducing a current in the entire disk

What is the unit of measurement for magnetic flux?

• Tesla

• Weber

• Newton

• Joule