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 Important Scientific Discoveries James Clerk Maxwell first formally postulated electromagnetic waves. These were subsequently confirmed by Heinrich Hertz. Maxwell derived a wave form of the electric and magnetic equations, thus uncovering the wave-like nature of electric and magnetic fields, and their symmetry. Because the speed of EM waves predicted by the wave equation coincided with the measured speed of light, Maxwell concluded that light itself is an EM wave. According to Maxwell's equations, a time-varying electric field generates a time-varying magnetic field and vice versa. Therefore, as an oscillating electric field generates an oscillating magnetic field, the magnetic field in turn generates an oscillating electric field, and so on. These oscillating fields together form a propagating electromagnetic wave.

The Electromagnetic Spectrum What are Electromagnetic Waves? Electromagnetic waves are transverse waves that transfer both electrical and magnetic energy. All electromagnetic waves consist of vibrating electric and magnetic fields that move through space at the speed of light (3.0 x 10^8 m/s)

The Electromagnetic Spectrum Producing Electromagnetic Waves Light is an electromagnetic wave All electromagnetic waves are produced by charged particles Protons are positively charged (+) Electrons are negatively charged (-) The electronic field produces electronic forces that push or pull on other charged particles.

The Electromagnetic Spectrum Producing A Magnetic Field A magnetic field is produced when a charged particle moves. The energy that is transferred through space by electromagnetic waves is called electromagnetic radiation Electromagnetic waves do not require a medium and therefore can travel through empty space (vacuum).

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. An electromagnetic wave is a transverse wave that transfers electrical and magnetic energy.

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 Electromagnetic Wave Models Sometimes light behaves like a stream of particles of energy. When a beam of light shines on some substances, it causes tiny particles called electrons to move and produce an electric current. Sometimes a beam of light can even cause electrons to be knocked out of substances. This is called the photoelectric effect. It can be explained only by thinking of light as a stream of tiny packets of energy. Each packet of light energy is called a photon.

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 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 All electromagnetic waves travel at the same speed in a vacuum, but they have different wavelengths and different frequencies. Recall: speed = wavelength x 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 FluorescentVaporNeon Bulb Material Hot/Cool Makeup Efficiency Quartz Glass HotVery HotCool 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 Producing Visible Light Glass 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 fieldsWavelengths Light Frequencies

The Electromagnetic Spectrum End of Section: Graphic Organizer