sceince

 Which wave represents an AM signal? How do you know?

   Answer: Wave B represents an AM signal. We know this because the amplitude (height) of the wave changes, but the frequency (number of waves per second) stays the same.

 * Which wave represents an FM signal? How do you know?

   Answer: Wave A represents an FM signal. We know this because the frequency of the wave changes, but the amplitude stays the same.

 * Which have higher frequencies, AM radio waves or FM radio waves?

   Answer: FM radio waves have higher frequencies than AM radio waves.

 * Which type of radio waves, AM or FM, produce better sound quality?

   Answer: FM radio waves produce better sound quality than AM radio waves.

 * What does GPS stand for?

   Answer: GPS stands for Global Positioning System.

 * Who can pick up GPS signals?

   Answer: Receivers can pick up GPS signals.

 * Amplitude modulation

   Answer: Amplitude modulation is a method of transmitting signals by changing the amplitude of a carrier wave.

 * Frequency modulation

   Answer: Frequency modulation is a method of transmitting signals by changing the frequency of a carrier wave.

Here is the text from the image you sent:

Wireless Communication

How Do Radio Waves Transmit Information?

Radio waves carry information from the antenna of a broadcasting station to the receiving antenna of your radio. Radio stations broadcast signals in two frequency bands.

 * Amplitude modulation (AM) is a method of broadcasting signals by changing the amplitude of a wave. The frequency of an AM wave is constant. AM waves have relatively long wavelengths and low frequencies and energy. They travel a greater distance than EM waves.

 * Frequency modulation (FM) is a method of broadcasting signals by changing the frequency of a wave. The amplitude of an FM wave is constant. FM waves have higher frequencies and more energy than AM waves. Radio waves are used for many types of communication. The FCC assigns different frequencies for different uses:

How Does a Cell Phone Work?

Cell phones transmit and receive signals using high-frequency microwaves. Cell phones work only if they are in a cellular system, which divides regions into many small cells. Each cell has one or more towers that relay signals to a central hub. The quality of your calls depends on the terrain and how close your cell phone is to a tower or a central hub.

How Does Satellite Communication Work?

Communications satellites receive radio, television, and telephone signals and relay the signals to receivers on Earth. Because a satellite can "see" only part of Earth at any time, more than one satellite is needed for any purpose.

 * In satellite phone systems, radio waves from one phone are sent up to a communications satellite. The satellite transmits the waves back to the receiving phone on Earth.

 * In satellite television systems, television signals are sent up to satellites. The satellites then relay the signals to customers' satellite dish antennas around the world.

Review and Reinforce

Waves of the Electromagnetic Spectrum

Understanding Main Ideas

Complete the table.

The Electromagnetic Spectrum

Type of Radiation

 * Radio waves

 * Microwaves

 * Infrared waves

 * Visible light

 * Ultraviolet rays

 * X-rays

 * Gamma rays

Example of Use

 * Radio and television broadcasts

 * Cooking food

 * Remote controls

 * Seeing colors

 * Sterilizing medical supplies

 * Seeing inside bodies

 * Killing cancer cells

Building Vocabulary

Answer the following questions in the spaces provided. Use a separate sheet of paper if you need more room.

 * What is the electromagnetic spectrum?

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

 * Why is too much exposure to ultraviolet radiation dangerous?

It can damage or kill living cells and burn skin.

 * What is a thermogram?

Shows regions of different temperatures in different colors.

 * How can a person detect infrared rays without an instrument?

You can feel the energy in heat. The waves make materials hot.

The Electromagnetic Spectrum

 * Radars and Satellites

 * Cooking food and WiFi

 * Handheld remotes, warming food

 * To see colors

 * Cleaning

 * Medical imaging and treating

 * To kill cancer cells

Radio Waves

Microwaves

Infrared Rays

Visible Light

Ultraviolet Rays

X-Rays

Gamma Rays

Sources:

 * Wavelength

 * Frequency

The Nature of Electromagnetic Waves

Understanding Main Ideas

Answer the following questions in the spaces provided.

 * What are the two kinds of fields that make up an electromagnetic wave?

   vibrating electric and magnetic fields

 * How does the photoelectric effect show that light has some properties of a stream of particles?

   by thinking of light as a stream of tiny...

   particles of energy

 * What model explains the behavior of light when light passes through a polarizing filter?

   The

   light of the flashlight gives through the

   first lens of the sunglasses but can't go through the other

Building Vocabulary

Fill in the blank to complete each statement.

 * The energy transferred by electromagnetic waves is called

   electromagnetic radiation

 * The photoelectric effect

   occurs when light hits a certain metal

   and causes electrons in that metal to move.

 * A(n) photon

   is a particle of light energy.

 * Light that passes through a polarizing filter is called

   polarized light

 * A(n) electromagnetic wave

   consists of changing electric and