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Electricity and
Magnetism
A Science A–Z Physical Series
Word Count: 1,668

Electricity
and Magnetism

Written by David Dreier

Visit www.sciencea-z.com

www.sciencea-z.com

Electricity
and Magnetism

Key elements Used in This Book
The Big Idea: Since the late 1800s, electricity has brightened our
homes and streets, powered our appliances, and enabled the
development of computers, phones, and many other devices we rely
on. Understanding what electricity is and how it becomes ready for
our safe use helps us appreciate this energy source. Meanwhile,
without magnets, we couldn’t generate electricity. Electricity and
magnetism, and the relationship between the two, are fundamental
to the workings of the modern world.
Key words: alternating current, amperes, atoms, attract, charge, circuit,
conductor, direct current, electric current, electricity, electromagnet, electrons,
generator, hydroelectric plant, insulator, ion, lines of force, magnetic field,
magnetism, north pole, nucleus, power plant, protons, repel, resistance, shock,
south pole, static electricity, transformer, turbine, volts, watt
Key comprehension skills: Identify facts
Other suitable comprehension skills: Compare and contrast; classify information;
cause and effect; elements of a genre; interpret graphs, charts, and diagrams;
using a glossary and boldfaced terms; using a table of contents and headings
Key reading strategy: Ask and answer questions
Other suitable reading strategies: Connect to prior knowledge; summarize;
visualize; retell
Photo Credits:
Front cover: © iStockphoto.com/Giles Angel; back cover: © Ron Giling/PhotoLibrary; title
page: © Dannyphoto80/Dreamstime.com; page 3: © iStockphoto.com/Mark Stay; page 4:
© Jupiterimages Corporation; page 8: © iStockphoto.com/Clint Spencer; page 9: © Image Source/
Corbis; page 10 (top left): © iStockphoto.com/Vinicius Ramalho Tupinamba; page 10 (top right):
© iStockphoto.com/John Scott; page 10 (bottom): © iStockphoto.com/Yunus Arakon; page 11:
© GIPhotoStock/Photo Researchers, Inc.; page 12 (left): © iStockphoto.com/Viacheslav Krisanov;
page 12 (right): © iStockphoto.com/Pixhook; page 13 (left): © iStockphoto.com/DSGpro;
page 13 (center left): © iStockphoto.com/Nasen Mann; page 13 (center right): © iStockphoto.com/
Hywit Dimyadi; page 13 (right): © iStockphoto.com/Gordon Dixon; page 15: © 3desc/
Dreamstime.com; page 16 (top): © iStockphoto.com/Matthew Cole; page 16 (bottom):
© Michael Newman/PhotoEdit; page 17: © Mary Evans Picture Library; page 18: © iStockphoto.com/
Billy Gadbury; page 19: © iStockphoto.com/Leif Norman; page 20 (top): © Aschwin Prein/
Dreamstime.com; page 20 (bottom): © Learning A–Z/Doug Tepper; page 21 (left):
© iStockphoto.com/Ekspansio; page 21 (right): © iStockphoto.com/Robert Dupuis; page 22:
© Eric Brow/Dreamstime.com
Illustration Credit:
pages 5–7,14: Learning A–Z

Written by David Dreier

Electricity and Magnetism
© Learning A–Z, Inc.
Written by David Dreier
All rights reserved.

www.sciencea-z.com

www.sciencea-z.com

Table of Contents

Introduction........................................................ 4
What Is Electricity?............................................ 5
The Two Kinds of Electricity............................ 8
Static Electricity................................................ 8
Electric Current............................................... 10
Measuring Electricity....................................... 13
What Produces Magnetism?........................... 14
Introduction

Magnetism and Electric Currents.................. 16
Producing Electricity.......................................
Steam...............................................................
Water...............................................................
Wind................................................................

17
18
19
20

Delivering Electricity....................................... 21
Electricity and Magnetism
in Today’s World......................................... 22
Glossary............................................................. 23
Index.................................................................. 24

3

Have you ever watched lightning during
a big storm at night? Did you know that a
lightning bolt is a natural form of electricity?
But most electricity is made by people. When
you turn on a light, you are using electricity
made by people. Electricity has become a very
important part of our lives. It’s hard to imagine
the world without it.
Magnetism is also a familiar part of our
world. Perhaps you have played with magnets.
Magnetism is closely related to electricity.
This book will teach you about electricity
and magnetism. And it will explain how
they are connected.
4

What Is Electricity?

Electrons Circle the Nucleus


You just learned that electricity can be
produced naturally. Or it can be made by
people. But what is electricity? It is a form of
energy. Energy is what makes things happen.
For example, the energy in sunlight makes
plants grow.

electron


proton
+/–
+





In diagrams, protons
have + signs on them,
and electrons have – signs
on them to show their
charges. Neutrons have +/–
because they have no charge.
This carbon atom has six electrons,
six protons, and six neutrons.

+/–
+

+

+

+/–

+/–

+

+/–



+

+
+/–

neutron



Charges of the same kind repel each other.
That means they push each other away.
Charges that are opposite attract each other.
So two protons or two electrons repel each
other. But a proton and an electron are
attracted to each other.

+

The number of protons and electrons in an
atom is usually equal. Because the charges are
equal in number, they cancel each other out.
The atom is neutral, meaning it has no charge.

+/–


+

+/–



Electrons quickly
orbit, or move in
a circle around,
an atom’s nucleus.



+/–
+/–

+/–

Electricity comes from atoms. Atoms are
very tiny particles. Everything in the world
is made of atoms. Inside each atom are even
smaller particles. They include ones called
protons and electrons. Those particles have
a feature called electric charge. Protons have
a charge that scientists call positive. Electrons
have an opposite
Particles Have Charges
charge, called

electron
negative. These
charges are the

proton
source of electricity.
+/–
+

+

+

neutron



5

6

An atom can gain an electrical charge. It can
do that by getting extra electrons. Or it can do
it by losing electrons.Atoms can gain or lose
electrons when they contact other atoms.

Static electricity is caused when particles
of opposite charge get separated. The two
kinds of particles are attracted to each other.
When the attraction becomes strong enough,
the particles quickly stream back together.
Lightning is caused in a storm cloud
when particles of opposite charge build
up in different areas. When the groups of
charges get large enough, they flow rapidly
back together. That causes a lightning flash.

positive and negative ions
Positive Ion

electron
proton







+

+

+

+

+

There are two kinds of electricity. They are
static electricity and electric currents.
Static Electricity

If an atom gets extra electrons, it has a
negative charge. If it loses electrons, the
protons will outnumber the electrons, so
the atom will have a positive charge. An
atom that has a charge is called an ion. An
atom with more electrons than protons is
a negative ion. An atom with more protons
than electrons is a positive ion.

+

The Two Kinds of Electricity

Negative Ion


+



+




neutron


+

+
+



Positive ions have more
protons than electrons.
Negative ions have more
electrons than protons.

+
+




+

+



Lightning that strikes the ground actually starts as a flow
of charge from the ground up to the cloud.



7

8

Electric Current
Lightning heats the air around it to about
30,000° C (54,000° F). That’s five
times hotter than the surface of the Sun!
Lightning also causes the air to expand
violently. That is what causes thunder.

An electric current is the flow of electrons
through a material. Materials that carry a
current are called conductors. Metals are the
best conductors, so electrical wires are made
of metal. Most wires that are used to carry
an electric current are made of copper.

Most lightning occurs up in the clouds.
But sometimes the separation of charges
happens between the ground and the clouds.
The particles then flow down to the ground.
This is the kind of lightning that strikes
buildings and trees.

Materials that do not conduct electricity
are called insulators. Rubber and plastic are
both good insulators. Most electrical wires are
wrapped in rubber. The rubber prevents shocks.

You can make a spark by scuffing your
shoes on a carpet when the air is dry. Doing
that causes your body
to pick up electrons
from the carpet.
Your body now has
a negative charge.
If you put your finger
near a metal object,
a spark will jump
from your finger.

insulators

conductors

insulators

Some tools have
plastic or rubber
handles to prevent
electric shocks.

Rubbing a balloon on your hair
can create a similar effect as
scuffing shoes on the carpet.

9

conductors

10

An electric current needs a complete path
in which to move. This path is called a circuit.
If a circuit is broken, the current stops flowing.








closed circuit
direct current


open circuit

With the circuit open,
or broken, electrons can
no longer flow, so the
lightbulb does not light up.

An electric current pushes against a force
in a wire. That force is called resistance.
Resistance causes a loss of energy. The
lost energy is released as heat.

11

alternating current

You have learned that there are two kinds
of electricity. There are also two kinds of
electric current. They are called direct current
(DC) and alternating current (AC). Batteries
use DC. The wall outlets in your home use
AC. The electrons in a DC circuit always
move in the same direction. The electrons in
an AC circuit move rapidly back and forth.
Both kinds of current create a flow of
electrical energy. That flow moves very fast.
When electrons start moving in a circuit,
energy fills the entire circuit right away.
This explains why a lamp lights up as soon
as you flip a switch.
12

What Produces Magnetism?

Measuring Electricity
Electrons need a push to get moving in
a wire. This push is called voltage. Voltage
is measured in units called volts. In most
cases, the more volts an energy source has,
the greater the push and flow of energy.
Most flashlight batteries have just 1.5 volts.
House wiring is about 120 volts.
The flow of current in a circuit is measured
in units called amperes. These units are
usually called amps for short. The more
electrons that are in motion in a wire, the
higher the number of amps. Another measure
used in electricity is the watt. It measures how
fast electrical energy is being used.
1.5 volts

12 volts

As you have learned, electricity and
magnetism are related. They are the two parts
of a force called electromagnetism. Magnetism
comes from the electrons in atoms. Electrons
spin like little tops. And every electron has an
invisible area of magnetism around it. This
area is called a magnetic field. In some metals,
the spinning electrons turn each atom into a
tiny magnet. Those atoms can be made to line
up in the same direction. Then the entire piece
of metal becomes magnetic. Most magnets are
made of iron.
non-magnetized
+


+
+


+

+
+

+
+



N+
++
+
+
+ + –
+






– S

9 volts
Batteries and outlets have different
volt levels that reflect how much
power they can deliver.

magnetized

220 volts / 110 volts

13

Some metals, such as
iron, can be magnetized.
A magnetic field forms
around the magnet.

14

S

N

N

You can see a magnet’s field.
Put the magnet under a piece of
paper and sprinkle flecks of iron
on the paper. The iron bits will
arrange themselves in lines of
magnetic force.

S

Opposite poles attract.
S

S

N

N

lines of force

Magnetism and Electric Currents

Like poles repel.

Magnets are strongest at their ends. These
ends are called poles. Like Earth, a magnet
has a north pole and a south pole. If you
cut a bar magnet into two halves, each piece
is a new magnet. Both of the new magnets
have a north and south pole.
A magnet’s poles behave like positive and
negative electrical charges. Two south or two
north poles repel each other. But the north
pole of a magnet is attracted to the south pole
of another magnet. A magnet is also strongly
attracted to iron and steel. That is because its
magnetic field creates a magnetic pull on the
atoms in the metal.
15

A magnet can be made with wire, an electric
current, and an iron bar. A wire carrying
current has a small magnetic field around it.
When a wire with current is coiled up, the
magnetic field gets stronger. If the wire is
wrapped around an iron bar, the bar becomes
a magnet. This type of magnet is called an
electromagnet. An electromagnet only works
when current
is moving
through the
wire. If the
current is
turned off,
the magnetism
What would happen to the paper clips
stops.
if the wire weren’t touching the battery?

16


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