1. Waves
Chapter 11 part 2

2. Definition of a Wave A wave is a vibration
That travels from place to place
Thus it is two motions each with its own direction
The Vibration: a SHM
The Propagation; its motion from place to place
Together they from a wave

3. Wave Types, by medium A vibration requires something to vibrate,
a “medium”
There are two types:
Mechanical : the medium has mass, such as…
Waves on a slinky, rope, water surface, sound etc.
Non-mechanical: such as…
Light, an electromagnetic wave
and
Gravity waves… a wave in space and time itself
(Gravity waves were recently detected an are no longer only theoretical!

4. Types by Relative Direction
If the directions of propagation and vibration are perpendicular, it is transverse wave Example: Ocean Wave, Wave on Rope If the directions of propagation and vibration are parallel it is longitudinal wave Example: Sound

5. Parts of a Wave
As a wave is a vibration it has the properties of a vibration…plus one more Its wavelength (λ), how far it goes during one cycle of vibration

6. Speed of a wave
The speed of a wave is determined by its wavelength and frequency
V = fλ

7. Interference What happens when two waves meet
Constructive
Waves meet in phase
Amplitude increases
Destructive
Waves meet out of phase
Amplitude decreases
Perhaps even canceling!

8. Reflected Waves
When a Wave reflects at a fixed boundary It becomes inverted
When a Wave reflects at a boundary where its is free to move It does not

9. Standing Waves
If waves are sent through a medium at the right frequencies
Reflected wave interfere with the new waves
Constructively and destructively at consistent places
Making a “stationary”
Or Standing Wave
Points of no vibration are called Nodes Points of maximum vibration are called Antinodes