Electromagnet lesson check

Which statement is true?

• As the electric current through a wire increases, the magnetic field around the wire becomes stronger.

• As the electric current through a wire increases, the magnetic field around the wire becomes weaker.

• As the electric current through a wire increases, the magnetic field around the wire is unaffected.

• As the electric current through a wire decreases, the magnetic field around the wire becomes stronger.

Which of the following conditions is necessary for a magnet inside a wire loop to produce an electric current?

• The magnet must be stationary.

• The wire loop must be part of an open circuit.

• The wire loop must already have a current running through it.

• The magnet must be in motion.

Which statement is false?

• The direction a magnet moves through a coil of wire determines the direction of the electric current.

• The direction a coil of wire moves through a magnetic field determines the direction of the electric current.

• Current will flow through a wire as long as the magnetic field around the coil is changing.

• Current will not flow through a wire if the magnet is outside the coil.

In the figure shown, what would happen if the direction of the current in the wire coil were reversed?

• The electromagnet would no longer work.

• The north and south poles would switch places.

• The strength of the magnetic field would increase.

• The strength of the magnetic field would decrease.

Which of the following is a way to increase the strength of an electromagnet?

• Decrease the current in the wire

• Increase the current in the wire

• Use fewer coils of wire

• Remove the iron core

How can the number of coils affect an electromagnet?

• More coils decrease the strength

• More coils increase the strength

• Fewer coils increase the strength

• The number of coils has no effect

What is the role of an iron core in an electromagnet?

• It decreases the magnetic field

• It increases the magnetic field

• It has no effect on the magnetic field

• It reverses the magnetic field

Which of the following is NOT a way to increase the strength of an electromagnet?

• Increase the current

• Increase the voltage

• Decrease the number of coils

• Insert an iron core

Increasing which of the following will NOT strengthen an electromagnet?

• Current

• Voltage

• Number of coils

• Resistance

What is one way to make an electromagnet stronger?

• Use a plastic core

• Use fewer coils

• Increase the current

• Decrease the voltage