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