1. The Energy of Waves

2. The Nature of Waves Wave Medium
periodic disturbance in a solid, liquid, or gas
energy being transferred through a medium or empty space
substance through which a wave can travel

3. Mechanical waves
Electromagnetic waves
waves that require a medium
ex. sound waves
do not require a medium
travel through emptiness of space and matter

4. Types of Waves Transverse waves
1. Crest
2. Trough
particles move perpendicularly to the direction the wave is traveling (up & down)
ex. electromagnetic waves
highest point on wave
lowest point on wave

5. Longitudinal Waves
1. Compression
2. Rarefaction
particles vibrate parallel to the direction of wave motion (back & forth)
ex. sound waves
particles are pushed together
particles are spread apart

7. Combination of transverse and longitudinal waves
Surface Waves
Combination of transverse and longitudinal waves
Wave motion is circular
Example-Ocean Wave

8. Properties of Waves Amplitude related to height
max distance from rest position
waves with large amplitude carry more energy

9. Wavelength
Frequency
distance between two crests or two compressions
shorter wavelengths = more energy
# of waves in a given time
measured in hertz (Hz)
1 Hz = 1 wave/sec
high frequency = more energy

11. Wave Speed
speed at which wave travels
speed = wavelength x frequency
v = λ x f
wavelength and frequency are inversely related

13. Wave Interactions Reflection Echo
wave bounces back after hitting a barrier
all waves can reflect
reflected sound waves

14. Refraction
bending of a wave as the wave passes from one medium to another at an angle
wave speed and wavelength changes
ex. rainbows – sunlight refracted through water droplets

15. Diffraction
bending of waves around a barrier or through an opening
depends on wavelength and size of barrier
ex. sound waves can be heard because they have longer wavelengths than light waves

16. Interference
Constructive Interference
Destructive
two or more waves overlapping
waves overlap to make larger crests/troughs – larger amplitude
crest of one wave overlaps the trough of another = smaller amplitude
waves with same crest/trough = no wave at all

18. Standing Waves
Resonance
pattern of vibration that simulates a wave that is standing still
only looks like it is still
ex. musician plucks a guitar string
two objects naturally vibrate at the same frequencies
ex. singing in the shower