Electricity and Magnetism Review

Electricity and Magnetism Review

Multiple Choice

You and your classmates are experimenting with things that can affect the strength of an electromagnet. The data table records the number of paperclips picked up by an electromagnet with 50 coils of wire at differing voltages. What conclusion can you draw from your data?

• The greater the voltage, the stronger the electromagnet.

• 
  An electromagnet with 50 coils is much stronger than an electromagnet with less coils.

• An electromagnet with a voltage of 6V is twice as strong as an electromagnet with a voltage of 3V.

• 
  An electromagnet with a voltage of 4.5V is three times as strong as an electromagnet with a voltage of 1.5V.

Multiple Choice

The attracting and repelling forces of magnets are used in countless objects, from refrigerator doors to maglev trains. Refrigerator doors use the attraction of magnets to stay closed, while maglev trains use magnetic repulsion to hover above rails. The center magnet in the picture is hovering between two magnets, making it appear to float.

 Which best explains how the center magnet is able to hover between two other magnets? 

• The opposite poles of each magnet are facing each other, so they repel.

• The magnets are stacked so that similar poles are facing one another.

• The middle magnet is repelling the top magnet while attracting the bottom.

• The middle magnet is attracted to the top magnet, but held down by gravity.

Multiple Choice

A student wants you to demonstrate that an electric current will produce a magnetic field.

Which set of objects could be used to demonstrate this?

• A battery, a coil of wire and a compass.

• A compass, some paper clips and a battery.

• A battery, an iron nail and a long copper wire.

• An iron nail, a permanent magnet and a battery.

Multiple Choice

The basic concept of how a simple motor works is explained by which statement?

• When a fan blows on a wire, it causes it to spin, creating a force.

• 
  When a fan blows on a wire, it causes it to spin, creating an electrical current.

• 
  When a wire that carries electrical current is placed in zero gravity, the wire experiences a force.

• When a wire that carries electrical current is placed in a magnetic field, the wire experiences a force.

Multiple Choice

Brady connected the loose wire to the battery and created an electromagnet. He picked up 45 thumb tacks with his electromagnet, though his goal was to pick up 50 thumb tacks. What could Braddy do to increase the strength of his electromagnet and pick up more thumbtacks?

• Use fewer coils of wire.

• Use a screw instead of a nail.

• 
  Use two batteries instead of one.

• Replace the nail with a piece of steel.

Multiple Choice

A student ran an experiment to test is heat had an effect on the strength of a permanent magnet. The student found that as the temperature of the magnet increased, the strength of the magnet decreased as shown in the table below.

 What is the most likely reason for this to happen?

• Heat caused the magnetic fields of the two poles to cancel out.

• 
  Heat caused the atoms (or domains) in the magnet to move out of alignment.

• 
  Heat caused a change in the state of matter from a solid to a liquid.

• Heat caused a chemical reaction to occur in the magnet.

Multiple Choice

Students hypothesized that by running an electric current through the wire of the apparatus shown here, they could cause a non-magnetic nail to exhibit magnetic properties. What would be a reasonable way to test this?

• Weigh the nail first while before turning the current on and again while the current was on.

• Put the nail in water before turning the current on and again after turning the current off.

• 
  Examine the nail under a microscope before turning the current on and again after turning the current off.

• See if iron filings will stick to the nail before turning the current on and again while the current was on.