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The Electromagnetic Spectrum

The Nature of Electromagnetic Waves


Waves of the Electromagnetic Spectrum


Producing Visible Light


Wireless Communication







Table of Contents

The Electromagnetic Spectrum

The Nature of
Electromagnetic Waves

Electromagnetic Waves

Believe it or not, you are being “showered” all the time, not
by rain but by waves.

The Electromagnetic Spectrum

The Nature of
Electromagnetic Waves

What Is an Electromagnetic Wave?

An electromagnetic wave consists of vibrating electric and
magnetic fields that move through space at the speed of
light.

The Electromagnetic Spectrum

The Nature of
Electromagnetic Waves

Models of Electromagnetic Waves

Many properties of electromagnetic waves can be explained
by a wave model. Only some light waves pass through a
polarizing filter. The light that passes through vibrates in only
one direction and is called
polarized light
.

The Electromagnetic Spectrum

Outlining

An outline shows the
relationship between
main ideas and
supporting ideas. As
you read, make an
outline about
electromagnetic
waves. Use the red
headings for the main
ideas and the blue
headings for the
supporting ideas.

The Nature of
Electromagnetic Waves

The Nature of Electromagnetic Waves

I.
What Is an Electromagnetic Wave?

A.
Producing Electromagnetic
Waves

B.
Energy

C.
Speed

II.
Models of Electromagnetic Waves

A.
Wave Model of Light

B.
Particle Model of Light

The Electromagnetic Spectrum

Electromagnetic Waves

Click the Video button to watch a movie about
electromagnetic waves.

The Nature of
Electromagnetic Waves

The Electromagnetic Spectrum

Links on the Nature of Waves

Click the SciLinks button for links on the nature of waves.

The Nature of
Electromagnetic Waves

The Electromagnetic Spectrum

End of Section:

The Nature of
Electromagnetic
Waves

The Electromagnetic Spectrum

Waves of the
Electromagnetic Spectrum

What Is the Electromagnetic Spectrum?

The electromagnetic spectrum is the complete range of
electromagnetic waves placed in order of increasing
frequency.

The Electromagnetic Spectrum

Scientific Notation

Frequencies of waves often are written in scientific notation.
A number in scientific notation consists of a number
between 1 and 10 that is multiplied by a power of 10. To
write 150,000 Hz in scientific notation, move the decimal
point left to make a number between 1 and 10:




In this case, the number is 1.5. The power of 10 is the
number of spaces you moved the decimal point. In this case,
it moved 5 places:


150,000 Hz = 1.5 X 10
5

Hz

Waves of the
Electromagnetic Spectrum

The Electromagnetic Spectrum

Scientific Notation



Practice Problem



A radio wave has a frequency of 5,000,000 Hz. Write this
number in scientific notation.

5.0 X 10
6

Hz

Waves of the
Electromagnetic Spectrum

The Electromagnetic Spectrum

Electromagnetic Waves

Electromagnetic waves are all around you

in your home,
your neighborhood, and your town.

Waves of the
Electromagnetic Spectrum

The Electromagnetic Spectrum

Electromagnetic Waves Activity

Click the Active Art button to open a browser window and
access Active Art about electromagnetic waves.

Waves of the
Electromagnetic Spectrum

The Electromagnetic Spectrum

Previewing Visuals

Before you read, preview Figure 3. Then write two questions
that you have about the diagram in a graphic organizer like
the one below. As you read, answer your questions.

The Electromagnetic Spectrum

Q
. Which electromagnetic waves have the shortest wavelength?

A
. Gamma rays have the shortest wavelength.

Q
. Which electromagnetic waves have the lowest frequency?

A
. Radio waves have the lowest frequency.

Waves of the
Electromagnetic Spectrum

The Electromagnetic Spectrum

Electromagnetic Spectrum

Click the Video button to watch a movie about

the electromagnetic spectrum.

Waves of the
Electromagnetic Spectrum

The Electromagnetic Spectrum

End of Section:

Waves of the
Electromagnetic
Spectrum

The Electromagnetic Spectrum

Producing

Visible Light

Incandescent Lights

An incandescent light is a light bulb that glows when a
filament inside it gets white hot.

The Electromagnetic Spectrum

Producing

Visible Light

Neon Lights

A neon light is a sealed glass tube that contains neon gas.

The Electromagnetic Spectrum

Feature

Comparing and Contrasting

As you read, compare and contrast the five types of light
bulbs by completing a table like the one below.

Glass

Ordinary
Light Bulb

Tungsten
-
Halogen

Fluorescent

Vapor

Neon

Bulb
Material

Hot/Cool

Makeup

Efficiency

Quartz

Glass

Glass

Hot

Very Hot

Cool

Tungsten filament
and nitrogen gas
and argon gas
inside

Has tungsten
filament and a
halogen gas inside

A gas and a
powder coating
inside

Has neon or argon
gas and solid
sodium or mercury
inside

Has neon gas
inside

Not efficient

More efficient
than ordinary
bulb

Very efficient

Very efficient

Producing

Visible Light

Glass

Cool

Cool

Very efficient

The Electromagnetic Spectrum

Data Sharing Lab

Click the PHSchool.com button for an activity about sharing
data for the Consumer Lab
Comparing Light Bulbs
.

Producing

Visible Light

The Electromagnetic Spectrum

End of Section:

Producing
Visible Light

The Electromagnetic Spectrum

Wireless

Communication

Radio and Television

In AM transmissions, the amplitude of a radio wave is
changed. In FM transmissions, the frequency is changed.

The Electromagnetic Spectrum

Comparing Frequencies

The table shows the ranges of
radio broadcast frequencies
used for AM radio, UHF
television, FM radio, and VHF
television.

Wireless

Communication

The Electromagnetic Spectrum

Comparing Frequencies

Kilohertz (kHz) and
megahertz (MHz)

Interpreting Data:


In the table, what units of
measurement are used for
frequency?

Wireless

Communication

The Electromagnetic Spectrum

Comparing Frequencies

UHF television uses the
highest frequency radio
waves, and AM radio
broadcast uses the lowest
frequency radio waves.

Interpreting Data:


Which type of broadcast
shown in the table uses the
highest frequency radio
waves? Which uses the
lowest frequency waves?

Wireless

Communication

The Electromagnetic Spectrum

Comparing Frequencies

UHF television uses waves
with the highest frequency
and therefore the shortest
wavelength.

Calculating:


Which type of broadcast uses
waves with the shortest
wavelength?

Wireless

Communication

The Electromagnetic Spectrum

Comparing Frequencies

You cannot tell from this data
if it is a television or radio
program, because VHF
television and FM radio both
broadcast radio waves with a
frequency of 100 MHz.

Inferring:


A broadcast uses a frequency
of 100 MHz. Can you tell from
this data if it is a television or
radio program? Explain.

Wireless

Communication

The Electromagnetic Spectrum

Wireless

Communication

Cellular Phone System

In the cellular phone system, cellular phones transmit and
receive radio waves that travel to the nearest tower.

The Electromagnetic Spectrum

Wireless

Communication

Communication Satellites

In the Global Positioning System (GPS), signals from four
satellites are used to pinpoint a location on Earth.

The Electromagnetic Spectrum

What You Know

What You Learned

Using Prior Knowledge

Your prior knowledge is what you know before you read
about a topic. Before you read, write what you know about
wireless communication in a graphic organizer like the one
below. As you read, continue to write what you learn.

1.
Cellular phones don’t use wires.

2.
Radio and television signals travel through the air.

1.
The signals for radio and television programs are carried by
radio waves.

2.
The signals can be transmitted by changing either the
amplitude or the frequency of the radio waves.

3.
Cellular phones transmit and receive signals using
microwaves.

Wireless

Communication

The Electromagnetic Spectrum

Links on Using Waves to Communicate

Click the SciLinks button for links on

using waves to communicate.

Wireless

Communication

The Electromagnetic Spectrum

End of Section:

Wireless
Communication

The Electromagnetic Spectrum

Graphic Organizer



Magnetic
fields

Electromagnetic
waves

consist of

travel at the
speed of

have different

Electric fields

Wavelengths

Light

Frequencies

The Electromagnetic Spectrum

End of Section:

Graphic Organizer