1. Unit 7 Waves
Chapter 11
Pages

2. Waves Waves travel through a medium Can be solid, liquid, or gas
Waves transport energy
A wave is a repeating movement that transfers energy through matter or space.
Light waves and radio waves do not need a medium in order to travel through space.

3. Types of Waves
Transverse – matter moves at right angles as wave travels
Ex: water moves up and down, ocean wave moves to the right

4. Compressional wave – matter moves in the same direction as wave travels
Ex: pulse through a slinky
Sound waves
The less dense area next to the compression is called the rarefaction.

5. Seismic waves are both

6. Wave Properties
Wavelength – distance between one point on a wave and the nearest point just like it
Frequency – how many wavelengths pass a fixed point each second (in Hertz)
Amplitude – measure of energy in a wave, from the rest position to either the crest or the trough
In compressional waves, the denser the medium, the larger the amplitude.

8. Equation Time! v = velocity (in m/s) Lambda = wavelength (in m)
f = frequency (in Hz or wavelengths/s)
v = lambda x f

9. Calculating Wave Speed
A wave has a wavelength of 2m and a frequency of 3Hz. What is its speed?

10. Reflection
Reflection occurs when a wave strikes an object and bounces off
All waves can be reflected
The Law of Reflection- The angle of incidence is equal to the angle of reflection

11. Refraction
Refraction is the bending of a wave caused by a change in its speed as it moves from one medium to another
The greater the change in speed, the more the waves bends

12. Moving into a medium in which it slows down, the wave refracts toward the normal
Ex: light moves from air to water
Moving into a medium in which it speeds up, the wave refracts away from the normal
Ex: light moves from water to air

13. Diffraction
Diffraction occurs when an object causes a wave to change direction and bend around it
Refraction= passing through
Diffraction= going around an object
The larger the obstacle compared to the wavelength, the less diffraction
AM radio waves diffract more than FM waves so reception is better

14. Interference When two or more waves overlap and combine 2 types:
1. Constructive- the waves add together
2. Destructive- the waves subtract from each other

15. Standing Waves
Waves of equal wavelength and amplitude, traveling in opposite directions, continuously interfere with each other
Place where they cross and cancel each other are called nodes
Musical instruments produce standing waves

16. Resonance
The natural frequency of a bell’s vibration depends on the bell’s size, shape, and material
The ability for an object to vibrate by absorbing energy at it’s natural frequency is called resonance
Ex: tuning fork