1. Mr. Jackson
Ch 20

2. What is a Wave?
A disturbance that transmits energy through matter or empty space
Energy can be carried away from its source by a wave.
If you drop a rock on a lake the rock will form a wave but the wave will not move any object on top of the water. See Ex

3. Medium A medium is a substance through which a wave travels.
The plural of medium is media
Sound waves require a medium whereas light waves do not.

4. Waves that Need a Medium are called mechanical waves
Waves that Need a Medium are called mechanical waves. Earthquakes are a good example of a mechanical wave

5. Energy Transfer Without a Medium
Visible light, microwaves, TV and Radio Waves as well as X-Rays are waves that do not require a medium

6. Transverse Waves
This is what you would think of when you think of a wave
A wave in which the particles of the medium move perpendicularly to the direction of wave travel

7. Longitudinal waves Looks like a slinky or spring
When the particles of the medium move in the direction of the wave.
When the spring’s rings are close together the part of the wave is called a compression
When they are pulled apart they are called rarefactions

9. Amplitude Amplitude is the Maximum distance a wave travels from its rest position

10. Wavelength
The distance from any point on a wave to an identical point on another wave

11. The shorter the wavelength the more energy a wave has

12. Frequency Expressed in Hertz Hz 1 wave in 1 sec = 1 Hz
103.7, ect

13. FM FM Radio represents Frequency Modulation
When The Frequency of a wave is modulated the Wave’s Frequency is refocused as it is transmitted

14. AM AM is Amplitude Modulation
This is where the wave’s Amplitude is refocused when broadcasted

15. Wave Speed
Wave speed is calculated by Multipling Wavelength x Frequency

16. More on Wave properties
As a wave’s Frequency is doubled the wavelength is cut in half
If wavelength is doubled the Frequency is cut in half

17. Reflection
Reflection is the bouncing back of a wave when it hits a barrier
All waves can be reflected
If a wave passes through a substance is it said to be transmitted

18. Refraction The Bending of a wave
When a wave passes from one medium to another it changes its speed and wavelength therefore it bends

19. Diffraction
The change of direction by a wave when it encounters a barrier.
Ex Sound coming from around a corner

20. Interference
When 2 or more waves overlap and form 1 wave

21. Constructive interference
When the crest of 1 wave overlaps the crest of another wave.
The result is a wave with higher amplitude

22. Destructive interference
When the crest of one wave overlaps with the trough of another wave
This reduces the amplitude

23. Standing waves
In a standing wave one part of the wave is always at rest due to total destructive interference.
Other parts of the wave have a high Amplitude
A standing wave appears to be standing still
Playing a guitar produces standing waves

24. Resonance
When an object close to the source object vibrating begins to vibrate
All musical instruments resonate to produce loud full sounds