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.
