1. WAVES
Definition:
A traveling disturbance that carries energy through matter and space
Waves transfer energy without transferring matter.
Waves are produced by something that vibrates.
**A traveling disturbance that carries energy through matter and space
**Waves transfer energy without transferring matter.
**Waves are produced by something that vibrates.
***Picture of the pond: Energy is carried by the wave, moving from place to place. The water itself goes nowhere. This can be seen by watching a leaf floating in the water. The leaf bobs up and down but doesn’t travel with the waves. Think about floating in the lake on an inner tube… a boat comes by and generates waves in the water. Describe your movement in the water.

2. WAVES Vibrations: Movement that follows the same path, repeatedly
Most waves are caused by a vibrating object.
**Movement that follows the same path, repeatedly.
**Most waves are caused by a vibrating object.

3. WAVES Mechanical Waves: Waves that require a medium
Two types: transverse and compression (longitudinal)
Examples are seismic and sound waves.
Medium: matter (the stuff) through which a wave travels
Examples include water, air, and solids.
**Medium: matter (the stuff) through which a wave travels
**Examples include water, air, and solid material.

4. TYPES OF WAVES TRANSVERSE COMPRESSION (LONGITUDINAL)
Movement of the medium is perpendicular to the propagation of the wave.
Examples – electromagnetic waves, waves on a rope, water waves
Draw an example in your notes. (Think of the slinky.)
COMPRESSION
(LONGITUDINAL)
Particles in a medium vibrate parallel to the propagation of wave motion.
Example – sound waves

5. Parts of a Wave Crest: high point of the wave form
Trough: low point of the wave form
Compression: more dense region of a longitudinal wave
Rarefaction: less dense region of a longitudinal wave
crest
**Crest: high point of the wave form
**Trough: low point of the wave form
**Compression: more dense region of a longitudinal wave
**Rarefaction: less dense region of a longitudinal wave
Rest position
trough

6. Wave Properties Wavelength:
Defined - distance between one point on a wave and the nearest point just like it Distance from…
1) Crest to crest 2) Trough to trough 3) Start of one compression to the next 4) Start of one rarefaction to the next
wavelength
**distance between one point on a wave and the nearest point just like it
distance from crest to crest OR
trough to trough OR
start of one compression to the start of the next compression OR
start of one rarefaction to the start of the next rarefaction
wavelength
wavelength
wavelength
Rest position

7. Wave Properties Frequency:
Defined - The number of wavelengths (or number of vibrations) that pass a fixed point each second
Frequency is expressed in hertz (Hz).
A frequency of 1 Hz means that one wavelength (or one vibration) passes by in one second. Two vibrations per second is 2 Hz.
In SI units, 1 Hz is the same as 1/s.
**The number of wavelengths (or number of vibrations) that pass a fixed point each second

8. Wave Properties Period: T = 1/f
Defined - the amount of time it takes one wavelength to pass a point, measured in seconds
T = 1/f
As the frequency of a wave increases, the period decreases.
**the amount of time it takes one wavelength to pass a point; measured in seconds.

9. Wave Properties Wavelength and Frequency:
The relationship is inversely proportional:
Wavelength (λ)
Wavelength (λ)
Frequency (f)
Frequency (f)

10. Wave Properties Wave Speed:
Depends on… the medium it is traveling through.
Sound waves travel faster in liquids and solids than they do in gases. However, light waves travel more slowly in liquids and solids than they do in gases or in empty space.
Sound waves travel faster in material when the temperature of the material is increased.
**Depends on the medium it is traveling through. Sound waves usually travel faster in liquids and solids than they do in gases. However, light waves travel more slowly in liquids and solids than they do in gases or in empty space. Also, sound waves usually travel faster in material when the temperature of the material is increased.

11. Wave Properties v = ƒ λ (m/s) Wave Speed (continued): ƒ = v / λ (Hz)
Calculated by multiplying its frequency times its wavelength
speed (in m/s) = frequency (in Hz) x wavelength (in m)
v = ƒ λ (m/s)
ƒ = v / λ (Hz)
λ = v / ƒ (m)

12. Wave Properties Amplitude and Energy:
Amplitude is related to the energy transferred by a wave.
The greater the wave’s amplitude, the more energy the wave transfers.
**Amplitude is related to the energy transferred by a wave. The greater the wave’s amplitude, the more energy the wave transfers.

13. Wave Properties λ λ crest amplitude amplitude trough
**Draw a picture, and label it in your notes. λ
trough

14. Reflection
When a wave comes to the end of the medium it is traveling in, it is partially reflected back.

15. Types of Mirrors
Plane
Convex
Concave

16. Refraction
When a wave crosses a boundary between mediums and its velocity changes as a result, the transmitted wave may move in a different direction than the incident wave (“bent”).

17. Snell’s Law Sin(θ)1 n1 = Sin(θ)2 n2 n – index of refraction
nair = Θ = 30°
nwater = 1.33

18. Diffraction
Process of waves bending around obstacles

19. Interference
When 2 waves pass through the same region of space at the same time. The resultant displacement is always the sum of the separate (component) displacements.
Constructive Interference: Add Together Destructive Interference: Cancel Each Other Out

20. Constructive vs. Destructive
Combined
waveform
Wave 1
Wave 2
Two waves in phase Two waves 180° our of phase