Download Chapter 7 Magnetism: Magnets

Chapter 7 Magnetism
Lesson 1 Magnets
Main Idea
Like magnetic poles repel each other and unlike poles attract each
other. Compasses use magnets to tell direction.
Vocabulary
o Magnetic force (330) – a force that pushes apart or pulls objects
together
o Magnets (330) – any object with magnetic force
o Poles (331) – parts of a magnet where the magnetic force is the
strongest
Magnetic field (334) – area of magnetic force around a magnet
o Compass (336) –an instrument that uses Earth’s magnetic field to
help people find directions
What is a magnet?
Main Idea
Magnets are objects that attract or repel other objects.
Supporting Details
A. A magnet is any object that can attract or repel other objects.
B. A magnetic force is as the ability magnets have to push apart or
pull together objects.
C. Magnetic Poles
1. Magnetic poles are the parts of the magnet that the magnetic
force is the strongest.
2. All known magnets have a north pole and a south pole
a. A north pole repels another north pole
b. A south pole repels another south pole
c. A north pole is attracted to a south pole
d. A south pole is attracted to a north pole
3. The strength of the magnetic force is dependent on how close
the objects are to each other.
a. The force is strongest when the two objects are close
together.
b. The force weakens as the objects are farther apart.
c. Magnets that are far apart do not push or pull
D. Refrigerator Magnets
1. Refrigerator magnets are made of tiny strips of magnets placed
next to each other.
2. The placement of the strips makes the magnetic force strong on
one side and weak on the other.
How do magnets attract?
Main Idea
All magnets have two poles. Like poles repel each other. Unlike poles
attract each other.
Supporting Details
A. Magnets can attract objects made of iron, cobalt, or nickel.
1. Magnets can also attract an alloy containing one of the above
metals (i.e. stainless steel).
2. When you bring a magnet near the object, the metal mecomes
magnetic.
B. Most magnets are made of metals
1. Metals, like all matter, are made up of tiny particles called
atoms.
2. The particles are like tiny magnets
a. The tiny particles are lined up.
b. The north poles face one direction
c. The south poles face the other direction
d. The particles push and pull in the same direction
C. Objects made of metals like iron, nickel, cobalt have magnetic
particles that push and pull in all directions.
1. When a permanent magnet is brought near the object, the
particles turn around and line up.
2. The metal becomes a temporary magnet.
3. It can attract other magnets.
4. When you take away the permanent magnet, the particles move
around again.
D. Sometimes the particles stay lined up and the metals become
permanent magnets.
1. Computer use magnets to write on hard disks.
2. They make some metals on the disk magnetic.
What is a magnetic field?
Main Idea
A magnetic field is the region of magnetic force around a magnet.
Supporting Details
A. Every magnet has a magnetic field around it.
1. A magnetic field is the area of magnetic force around a magnet
2. When another magnet enters the magnetic field, it is either
attracted or repelled without touching the magnet.
3. A magnetic field is strongest near the poles and weaker the
farther away from the poles.
B. Much of the inside of the Earth is made of melted iron. The iron
creates a magnetic field around the Earth.
C. Earth spins around its axis
1. The geographic north pole is located at one end of the axis.
2. The geographic south pole is located on the opposite end
3. Earth has one magnetic pole near its geographic north pole and
another one near the geographic south pole
What is a compass?
Main Idea
A compass needle is attracted to Earth’s magnetic poles so it can be
used to find which way is north.
Supporting Details
A. A compass is an instrument that uses Earth’s magnetic field to help
people find directions.
B. A compass is a thin magnet that points to the Earth’s magnetic
north pole.
C. A compass can be used to determine north, south, east, west and
other directions in between.
D. A compass does not point towards the Earth’s geographic north
pole.