1. Electromagnetic Waves
Chapter 13

2. Section 1: What are E-Waves?
Electromagnetic Waves are made by vibrating electric charges and can travel through space

3. Electric and Magnetic Fields
They are related forces that operate even in empty space.
A moving electric charge creates a magnetic field.

4. EM-wave Production
EM waves are produced when an electric charge is vibrating.
Vibrating charges are surrounded by vibrating magnetic and electric fields.
These fields travel outward from the moving charge

5. EM field - Properties
They carry radiant energy
As frequency increases; wavelength decreases.
Frequency is number of vibrations per second.

6. EM – Wave Speed
Wave speed – in a vacuum of space; is 300,000 km/s
EM waves slow as they travel through matter.

7. Waves and Particles
Differences between the two are not clear
Light can behave as a particle called a photon, whose energy depends on frequency.
All particles can behave like a wave.

8. Section 2: Electromagnetic Spectrum
The entire range of the electromagnetic wave frequencies is called the EM-Spectrum.

10. The EM Spectrum is arranged by the frequency of the wave.
Radio waves have the smallest frequency and longest wavelength.
Gamma rays have the largest frequency and shortest wavelength.

11. Radio Waves
Low-frequency
Wavelength less than 1 centimeter to about 1000 meters
a. Microwaves- radio wave length about 1 to 10 cm

12. Radio Waves-Continued
b. Radar-Radio waves bounced off an object to determine its speed and location.
c. Magnetic Resonance Imaging – (MRI) radio waves produce an image of the inside of the body.

14. Infrared Waves
EM waves with a slightly higher frequency than radio waves; people feel as thermal energy or warmth.

15. Visible Light
Has wavelengths between about 390 to 770 billionth of a meter, can be seen with the eye.

16. Visible Light Color Red- smallest frequency, longest wavelength Orange
Yellow
Green
Blue
Indigo
Violet- largest frequency, shortest wavelength

19. Ultraviolet Waves
Have frequencies slightly higher than visible light; can damage skin.

20. Ultraviolet waves-continued
1. Ultraviolet light can kill bacteria
2. Ultraviolet light can be absorbed by some fluorescent materials and released into visible light.
3. Ozone layer absorbs most harmful UV waves.

22. X-rays and Gamma Rays
Ultra-high-frequency EM waves that can travel through matter, break molecular bonds, and damage cells.

25. Continued
X-rays are used to show images bones and to examine suitcases at airports.
Radiation therapy is used to kill diseased cells.

26. Section 3: Radio Communication

27. Radio Transmission
A radio converts EM waves into sound waves.
Carrier wave is the specific frequency of the radio wave to which a radio station is assigned

28. Radio Transmission
AM radio stations broadcast signals by varying amplitude of the carrier wave.
FM radio stations broadcast signals by varying frequency of the carrier wave.

29. Television
Sounds and images changed into electronic signals broadcast by carrier waves

30. TV - Continued
Audio sent by FM radio waves
Video sent by AM radio waves
A sealed vacuum chamber called a cathode-ray tube has a screen that can turn electron beams into images.

31. Telephones
Microphone converts sound waves into electrical signals.
Cell phone – signal creates a radio wave that travel to and from a microwave tower.
Cordless phone – uses transceivers to send and receive radio signals.

32. GPS
Global Positioning System – system of satellites, ground stations, and receivers that provide information about someone’s location.