1. Unit 8 Electromagnetic Waves
Chapter 13
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2. Electromagnetic waves
Do not require matter to transfer energy because they are created by vibrating charges
Electric charges are surrounded by electric and magnetic fields
Waves are produced when charges move back and forth

3. Properties of Electromagnetic Waves
Energy carried by an electromagnetic wave is called radiant energy
They travel at 300,000 km/s (speed of light) in a vacuum
Travel slower in solids, faster in gases
Frequency and wavelength are the same concept as last unit’s transverse waves

4. Waves and Particles A wave is a disturbance that carries energy
A particle is matter that carries energy
Light can behave as a photon particle, whose energy depends on the frequency
All particles, including electrons, can behave like waves

5. The Electromagnetic Spectrum
Arranged by increasing frequency from left to right
Therefore, decreasing wavelength from left to right

6. Radio and Microwaves
Radio waves have the lowest frequency (longest wavelength)
Microwaves are used for communication
Also used in heating food by making the water molecules flip direction and bump into each other creating friction

7. Radar
Radar uses radio waves to find the position and movement of objects
RAdio Detecting And Ranging
The time it takes for the radio waves to bounce off the object and return

8. MRI Magnetic Resonance Imaging
Radio waves used to diagnose illnesses by measuring the amount of energy released by a proton based on the type of tissue where it is found

9. Infrared Waves Infrared waves transfer thermal energy
Has a frequency greater than radio and microwaves
Used in remote controls and computers
Hotter the object, the more IR waves emitted

10. Visible Light
The only range of the spectrum you can detect with your eyes
Shortest wavelength: violet (blue)
Longest wavelength: red
All the colors together appear as white light

11. Ultraviolet Waves Greater frequency than visible light
Can enter skin cells
Overexposure can cause sunburn
UVA- longer than UVB, so B is more dangerous
UV light helps your body produce Vitamin D

12. Useful UV
UV light kills bacteria on objects, so it can be used as a sterilization tool
Some objects fluoresce (glow) after absorbing UV light, so it can be used as a crime scene tool to show fingerprints, traces of blood, etc

13. Ozone Layer 3 oxygen molecules bonded together
Located in the stratosphere
Absorbs UV rays from the sun and protects life on earth
Thinnest over Antarctica due to CFC usage in the past

14. X and Gamma Rays
X rays have the 2nd highest frequency (Gamma has the highest)
Can travel through matter and are used in medical imaging as well as security
Radiation therapy used to kill diseased cells

15. Radio Transmission
Antenna detect radio waves, and transmit the signal to your radio where the vibrating electrons produce a signal that contains music
Each radio station is assigned to a specific frequency, called a carrier wave

16. AM and FM Radio AM stations vary the amplitude of the wave broadcasted
The electronic signal makes the speaker vibrate
FM stations vary the frequency, and since the strength is fixed the station usually comes in clearer than AM

17. Television Cathode ray tube
Sealed vacuum in which 3 electron beams are produced that sweep across the screen back and forth
Three colors of spots on the screen: red, green, and blue

18. Telephones
When you speak into a telephone, a microphone converts sound waves into an electric signal
Radio waves are then transmitted to and from a tower

19. Communication Satellites
Thousands have been launched into Earth’s orbit
Used for communication with cell phones and televisions
Satellite TV uses microwaves instead of radio waves (like cable does)

20. GPS Global Positioning System
System of 24 satellites that provide your exact location (latitude, longitude, and altitude)
Used by virtually everyone:
Emergency responders
Planes, ships, cars
Hikers