Magnetism and Electromagnetism

Which phenomenon is most directly responsible for Earth's magnetic field?

• Earth's rotation about its axis

• Earth's revolution around the sun

• the moon's revolution around Earth

• the moon's gravitational pull on Earth

What is a temporary magnet?

• One that is always magnetic

• One magnet that is controlled through an electric current

• a refrigerator magnet

• Does not have a north and south pole

Why are certain materials, such as copper and aluminum, not magnetic?

• The individual atoms that make up the materials do not have magnetic fields.

• The individual atoms that make up the materials align themselves into domains.

• The magnetic fields of the individual atoms that make up the materials cancel each other out.

• The magnetic fields of individual atoms that make up the materials are highly unstable and easily lost.

Some objects can be magnetized by rubbing one pole of an existing magnet in one direction along the object. Why?

• The motion of the existing magnet against the object aligns the magnetic domains of the object.

• The motion of the existing magnet against the other scrambles, or un-aligns, the magnetic domains of the object.

• The motion of the existing magnet against the object generates an electric current that transforms the object into an electromagnet.

• The motion of the existing magnet against the object wears away the object's surface, exposing the naturally occurring magnets underneath.

Joe has an idea to cut a bar magnet in half so that he can have one magnet with a north pole and one magnet with a south pole. What is wrong with this idea?

• It is impossible to cut a magnet in half.

• It is impossible to create an extremely small magnet.

• It is impossible to create a magnet with only one magnetic pole.

• It is impossible to separate two opposite magnetic poles once they are in contact with each other.

A photographer travels to Earth's north pole to photograph the aurora, a beautiful light display in the sky. Which of the following are most responsible for the formation of the aurora?

• Earth's rotation and revolution around the Sun

• static electricity and electric current in the atmosphere

• charged particles from the Sun and Earth's magnetic field

• electromagnetic induction and particles in the atmosphere.

Angela tries to pick up a copper penny using a bar magnet, but the penny does not move. Then she tries to pick up an iron nail using the bar magnet, and the nail lifts up towards the magnet. Her teacher tells her that the magnet lifts the iron nail because it is a ferromagnetic material. Which of the following best describes a ferromagnetic material?

• A material that easily conducts electricity

• A material that produces its own magnetic field

• A material with naturally strong magnetic properties

• A material made of non-metals that produce magnetic fields

Candice learns that all magnets have two magnetic poles. Which of the following observations would best support this statement?

• When a bar magnet is cut in half, each half has a north and south pole.

• The north pole of a compass needle is attracted to the south pole of a bar magnet.

• When an electric current flows through a wire, a magnetic field forms around the wire.

• The strength of a horseshoe magnet's magnetic field decreases as the magnet is pulled away from another object.

When particles from the Sun travel towards the Earth, the Earth's magnetic field pulls them towards the poles. These solar particles interact with particles in Earth's atmosphere and can create a beautiful light display in the sky. What light display is this commonly called?

• Aurora

• Geographic pole

• radiation belt

• solar flare

What is a permanent magnet?

• Has magnetic properties for a long time

• is magnetized by an electric current

• is not magnetized

• does not have a north or south pole