Checkpoint Review 9/25

A student connects a wire to one or more batteries and coils the wire around a steel rod. The student measures the number of identical steel washers that the electromagnet picks up and records the data in a table.

• decreasing the strength of the electric current increases the strength of the magnetic field

• increasing the strength of the electric current increases the strength of the magnetic field

• decreasing the number of wire coils increases the strength of the magnetic field

• increasing the number of wire coils decreases the strength of the magnetic field

A scientist wants to test different nails to determine which one makes the strongest electromagnet. The scientist selects an iron nail, steel nail, and copper nail to use in the investigation.

• 1. Wrap each nail with a different type of wire (zinc, brass, aluminum). 2. Record the number of paper clips each nail picks up.

• 1. Wrap each nail with as many coils as possible. 2. Record the nail that has the most coils.

• 1. Wrap each nail with 25 coils of copper wire. 2. Record the number of paper clips each nail picks up.

• 1. Wrap each nail with a different number of coils of copper wire. 2. Record the number of paper clips each nail picks up.

What can a car manufacturer do to make an electric motor stronger?

• A car manufacturer can add coils to the electromagnet and increase the size of the magnets causing the rotational motion.

• A car manufacturer can add coils to the electromagnet and decrease the size of the magnets causing the rotational motion.

• A car manufacturer can remove coils from the electromagnet and increase the size of the magnets causing the rotational motion.

• A car manufacturer can remove coils from the electromagnet and decrease the size of the magnets causing the rotational motion.

What materials did each group receive to build their electromagnet?

• An iron nail, 2 meters of insulated wire, a D-cell battery, and ten paperclips.

• A wooden stick, copper coins, a 9V battery, and five rubber bands.

• A plastic rod, 1 meter of string, a C-cell battery, and ten thumbtacks.

• A steel bolt, 3 meters of bare wire, a AA battery, and five magnets.

What is the purpose of wrapping the wire around the nail?

• To create an electromagnet by generating a magnetic field when electric current flows through the wire.

• To prevent the nail from rusting.

• To make the nail heavier.

• To insulate the nail from heat.

What happens to the compass needle when the circuit is open and the compass is placed near the coil?

• The compass points towards the coil

• The compass points in the direction of the North pole

• The compass spins rapidly

• The compass does not move

What happens to the compass needle when the circuit is closed and the compass is placed in the same position?

• The compass points towards the direction of the coil

• The compass points in the direction of the North pole

• The compass spins rapidly

• The compass does not move

What happens when the circuit remains closed and the coil is flipped so that the opposite side of the coil faces the compass?

• The compass points towards the direction of the coil

• The compass points towards the direction away from the coil

• The compass points in the direction of the North pole

• The compass does not move

Refer to the diagrams showing the compass and coil experiment. What happens to the compass needle when the circuit is opened again after being closed?

• The compass points towards the direction of the coil

• The compass points towards the direction away from the coil

• The compass points back in the direction of the North pole

• The compass does not move

Look at the labeled diagram of the simple motor. Name the part that is added to complete the motor design and causes the coil to spin when the circuit is connected.

• Permanent magnet.

• Battery.

• Switch.

• Insulated wire.