1. Waves

2. Wave : a disturbance that moves energy through space
1) the material that gets disturbed is the Medium
2) the medium does not travel through space it just bounces up and down or back and forth in place

3. 2 Types of Waves
1) Transverse: medium motion perpendicular to direction of wave (energy) travel

4. 2) Longitudinal: motion of medium is parallel to wave direction Medium bunches up into compressions and spreads out into rarefactions

5. Amplitude : max distance molecules displaced from rest position
Greater amplitude = more energy
= louder sound (more sound intensity)
= brighter light (more intense light)

6. Wavelength(ג) – distance between 2 consecutive rarefactions or compressions (crests or troughs)

8. Wavelength Determines type of electromagnetic wave
* radio wave vs visible light vs X-ray
* color of light

10. Frequency: # waves per second
How many waves pass a set point per second
1 wave/sec = 1 hertz
At set speed frequency = wavelength
So frequency of light also determines color
Frequency of sound = pitch
High frequency = high pitch
Ultrasonic – higher pitch
20 Hz – 20,000 Hz = audible sound
subsonic – lower pitch

11. Period = time for 1 wave to pass set point
Period = 1/frequency

12. Wave speed = how fast one crest is moving
Speed = frequency X wavelengths
Speed of light waves in a vacuum is constant
Light slows slightly if moving through a medium
Different mediums conduct waves at different speeds

13. 1. Waves are reflected when they bounce back from an object
Angle of incidence = between incident wave and normal (normal = line perpendicular to object)
Angle of reflection = between normal and reflected wave

14. Law of Reflection
Angle of reflection = angle of incidence

15. Diffuse reflection = many directions, rough surface,
fig p 256,
less glare
dry road

16. 2. Refraction – wave bends due to a change in speed
2. Refraction – wave bends due to a change in speed. Often as wave moves from 1 medium to another. (Water, air)
3. Diffraction – bending of waves around a barrier (p274)

17. 4) Interference = 2 waves combine to form a new wave
a. Constructive = crests overlap to create larger amplitude
b. Destructive = crest lines up with trough to cancel

18. Interference
Constructive
Destructive