CHAPTER 12LESSON 5
MAGNETISM&
ELECTRICITY
Reading with a Question in Mind
What is the biggest magnet in the world? Read pg. 578 in the science book your
teacher gave you to find out. Write your answer in the margin
at the top of the page.
A magnet is an object or a material that can attract metals containing iron, nickel, or cobalt.
Magnets can attract and repel each other.
All magnets have a north pole and a south pole
The north poles and south poles of two magnets will repel each
other.
The attraction of magnets is strongest when magnets are
close together.
A magnetic field is the area of magnetic force around a
magnet.
PLEASE DO NOW!Read the section on pg. 579
in the science book your teacher gave you entitled Using a
Compass to build your own compass with your partner.
In the margin of your paper explain
how a compass works.
An electromagnet is a coil of wire wrapped around a metal core; current moving through
the wire can be turned off with a switch.
Electromagnets are often used to power electric motors.
Almost all electricity is produced by generators.
Generators produce back-and-forth current called alternating
current. Batteries produce current in one direction, called
direct current.
Air, steam, and water
turn turbines.
Electricity from a power plant is carried to a series of
transformers.
Each transformer in the series increases or decreases the
current’s voltage until it is at the right level to enter your home.
EXIT ACTIVITYDo you think there is a difference between the simple motor used in the electric cars you parents may drive and the model cars
you and your friends may race?
All electric motors have a power source, a magnet, a rotating
loop of wire, and a motor shaft. The only difference is the type or size of the power source. If
model cars are remote controlled, then electromagnets can also be used to power the
electric motors.
EXIT ACTIVITY