1. Waves

2. What is a wave?
A wave is a repeating disturbance or movement that transfers energy through matter or space (transfers energy-NOT matter)
Types of waves
1. Water Seismic
2. Sound Radio
3. Light
4. Electromagnetic

3. What creates Waves? Anything that vibrates creates waves.
A wave will only exist as long as it has energy to carry it.
Vibrate: to move up & down/ back & forth in a rhythmic motion.
Mechanical Waves: waves that travel only through matter-solids/liquids/gases or combination of them.
Medium: the matter that waves travel through.

4. Two Types of Mechanical Waves
Transverse wave: a wave where the matter in the medium moves back and forth at right angles to the direction the wave travels; water wave.

5. Compression wave: (longitudinal) a wave where matter in the medium moves back and forth along the same direction that the wave travels; sound waves.
**The compression in a compression wave corresponds to the crest in a transverse wave***

6. Parts of a wave

7. How are waves different?
Transverse wave:
a. Crest: the highest point of a wave
b. Trough: the lowest point of a wave
c. Wave length: crest to crest or trough to trough
d. Frequency: count the # crests or # troughs that pass a
given point.
Compression wave:
a. Rarefaction: less dense region
b. Compression: region where the coils are close
together
c. Wave length: rarefaction to rarefaction or compression
to compression
d. Frequency: count the # compressions or rarefactions that pass a

8. Frequency: units expressed in Hertz (Hz)
Period: units expressed in seconds (s)
* A frequency of 1Hz means one wave length passes by in one second*
** Increase wave frequency, the period decreases & the wavelength decreases**

10. Amplitude
Amplitude: the amount of energy a wave carries.
The > amplitude, the more energy a wave carries.
How do you measure amplitude?
a. Compression wave: how tightly the medium is pushed together.
The denser the medium at compressions, the further apart they are at rarefactions, the > amplitude & the more energy the wave carries.
b. Transverse wave: the distance from the crest/trough of the wave to it's rest position.
The taller a wave, the > amplitude & the more energy the wave carries.

11. How do waves behave?
A. Reflection: waves strike an object and bounce off it; echo sound waves.
The Law of Reflection: the angle of incidence is = to the angle of reflection.

12. B. Refraction: waves bend when they have a change in speed when they move from one medium to another.
(the > the change in speed, the more the wave bends).

13. C. Diffraction: when an object causes a wave to change direction and bends around it.

14. D. Interference: when 2 or more waves overlap and combine to form a new wave.
a. Constructive Interference: 2 waves overlap and ADD together.
b. Destructive Interference: 2 waves overlap and subtract from each other.

16. Standing Waves
Standing Wave: wave patterns that occur when waves equal in wavelength & amplitude but moving in opposite directions continuously interfere with each other.

17. Resonance
Resonance: when an object vibrates by absorbing energy at its natural frequencies.