1. Waves General and Electromagnetic
Unit 9 Notes
Waves
General and Electromagnetic

2. Waves carry energy & information
The information carried could be:
Sound
Color
Pictures
Radio waves – tv
Microwave – cell phones
WAVES DO NOT CARRY THE MEDIUM!!! (Ex: water)

3. Transverse Waves Energy moves left to right Wave moves up & down
Ex: water waves
A Rope that is moved up and down
Light
Wave and energy move perpendicular to each other.

4. Also called Compressional Waves
Longitudinal Waves
Also called Compressional Waves
Wave and energy are in same direction
Ex: Slinky
The compression will move along the slinky forward and then back.
Sound

5. Parts Of A Transverse Wave
Crests: high point of the wave
Troughs: low point of the wave

6. Wavelength ( ): The length of one complete cycle of a wave.
From crest to crest or trough to trough.

7. Amplitude How big or little the wave is.
Tells you how much energy the wave has.
The bigger the wave, the more energy it has.

8. Parts of a Longitudinal Wave
Compression-The condensed portion
Rarefaction-The separated part of the wave.
Wavelength-distance from compression to compression

9. Frequency How many waves pass in 1 sec.
A wave carries its frequency to every area that it reaches
Measured in hertz (Hz)

10. Speed of a Wave How fast the wave can transfer energy. v = f x 
v = speed (velocity) Units=m/s
f = frequency Units=Hz
 = wavelength Units=m

11. TRANSVERSE WAVES!!!!
All travel at the same speed
The difference is in the frequency and the wavelength. If one goes up, the other goes down.

12. Parts of the EM Spectrum
Radio Waves-Longest wavelength, lowest energy, lowest frequency.
Used for TV’s, Radios and Cell Phones

13. Microwaves
A form of radio waves-some books place them separately and some put them in with radio.
They are the highest frequency (most energy) of the radio waves.

14. Infrared (IR) Heat Used to find people in the woods.
Infrared film detects how hot something is.
Use to detect cancer
Beneath red

15. Visible Light ROY G. BIV-colors of visible light.
Sunlight emits UV along with other rays.
Gives us Vitamin D
Too much harmful.
Most filtered by ozone.
Red is longest

16. ultraviolet Main source is sunlight Helps your body produce vitamin D
Overexposure = burns and skin cancer
Sunscreen helps to block
Beyond violet

17. X-rays Images of structure inside the human body X-rays-See bones.
Airport screening devices
Used to treat cancer

18. Gamma Rays High Energy Use thick lead to block!
Gamma rays-highest energy, shortest wavelength, highest frequency
Generated by radioactive atoms
Used to treat cancer

19. Wave Interactions
Interaction -Wave run into other object or another wave
Interaction can increase or decrease wave energy
Interaction can change the properties of the wave
Interaction can change the direction

20. Reflection A wave bouncing off of a surface
Mirror
Wave hitting a wall
Incident wave – moving to surface
Reflected wave – moving away from surface
Law of Reflection – wave bounces off the surface at the same angle that it entered the surface

21. Light reflection
Mirror
Radar –weather and flying object

22. Reflection of sound ECHO Concert halls want to minimize echo
Good acoustics
Bats use echolocation to find food at night

23. Sonar
Reflection of sound from the bottom of the ocean floor to detect depth or objects
Whales and dolphins use this also

24. Ultrasound Reflecting sound waves in the body
Used in medicine to monitor patients
Pregnancy
Heart disease
Cancer

25. Refraction Bending of wave as it changes speed
Speed changes from on medium to another
Air to water
Water to oil

26. Diffraction
Bending of a wave when it comes into contact with the edge of another object
Light bending around a door

27. Interference The effect of 2 or more waves interacting
Can be constructive or destructive

28. Constructive Interference
Wave crest come together at the same location
Waves join together to make a larger wave

29. Destructive Interference
The crest of one wave meets the trough of another wave
Crest and trough subtract from each other to make a smaller wave
Sometimes the interference cancels both waves

30. Polorization
Unpolarized light contains light waves moving in all directions
We can use filters to stop waves traveling in certain directions

31. Polarizers Used in Sunglasses Photography Windsheilds Digital watches
Laptop screens