chapter 8 cornell

south and north

attract

The strength of the magnets _________ as they get farther apart

decreases

The strength of the magnets _________ as they get closer together

increases

A magnetic field _______ the magnet

surrounds

What happens when a magnet is broken in two?

Each piece gains a north and south pole and becomes its own magnet

Why does the north pole of the compass needle point north?

Because the Earth acts like a giant bar magnet and is surrounded by a magnetic field that extends into space. Just as with a bar magnet, the compass needle aligns with Earth's magnetic field lines

How can a compass help determine direction?

Because the north pole of the compass needle points north.

What makes an element magnetic?

Electrons have magnetic properties, however in the atoms of most elements, the magnetic properties of those electrons cancel out.

Where was the natural magnet found?

In a region of Turkey that was called Magnesia

In what metals are the magnetic properties of the electrons not canceled out?

Iron, cobalt, and nicel

How is a magnetic field represented?

It is represented in a pattern, a curved rainbow of lines over and around the magnet starting at both ends of the poles

Where does the name Magnetic come from?

Magnesia, where the first magnet was found

lining up domains

Poles need to be lined up for material to be magnetic. Heat can effect and demagnetize

What happens when you sprinkle iron filings around a magnet?

The Iron filings line up along the magnetic field lines

What happens if you place a magnet against a nail?

The atoms in the domains orient themselves in the direction of a nearby magnet

If the external magnetic field is removed, what happens?

The constant motion and vibration of the atoms bump the magnetic domains out of their alignment and the magnetic domains in the nail return to random arrangement.

compass needle

a small bar magnet that can freely rotate

Which magnets have a north pole and a south pole?

all magnets

north and south

attract

What did Greeks discover?

deposits of mineral that was a natural magnet

Magnetic Field

exerts a force on the other magnets and objects made of magnetic materials

magnetic domains

groups of atoms with aligned magnetic poles

What produces earth's magnetic field?

no one is sure

South pole of a magnet

points south and is called the south seeking pole

north and north

repel

south and south

repel

compass

something used to tell direction, operated by magnets and containing North, South, East, West, Northeast, Southeast, Northwest, Southwest

What can you notice when you are playing with magnets?

that they exert a force on each other

North pole of a magnet

the end of the magnet that points toward the geographic north.

Earth's magnetic poles

the poles of the magnetic field that surrounds the Earth

when two magnets are brought close together, what happens to the magnetic fields?

they combine to create one magnetic field

Magnetic Poles

two ends of a magnet where the magnetic forces are strongest

What determines weather magnets repel or attract each other?

which ends of the magnets are close together

Describe how a compass works

When a compass is brought near a bar magnet, the compass needle rotates. The compass needle is a small bar magnet with a north pole and a south pole. The force exerted on the compass needle by the magnetic field causes the needle to rotate. The compass needle rotates until it lines up with the magnetic field lines. The north pole of a compass points in the direction of the magnetic field. This direction is always away from a north magnetic pole and toward a south magnetic pole.