1. Waves! …Of all kinds

2. What are waves? Wave – Energy that is transferred through a medium, or a source. Wave – Energy that is transferred through a medium, or a source. What’s energy? What’s energy? –The ability to do work.

3. There are two kinds of waves 1.Mechanical 2.Electromagnetic

4. Mechanical Waves Ex. Ocean Waves Ex. Ocean Waves Need a medium: Need a medium:  a material through which a wave travels. * Note this is only true for mechanical waves * Electromagnetic waves can travel through empty space!

5. How do waves transfer energy? Do waves move material? Do waves move material? –Yes, but not the way you think it does. –Material does not move in the same direction as the energy. –Have you ever gone to the beach and waited for a good body surfing wave?

6. Waves Wave motion Wave motion –The wave moves water up and back toward the crest –Then down and forward toward the trough. –Water moves in little circles! –Only the energy moves. –WATCH!

20. What causes waves? Mechanical waves are produced when a source of energy causes a medium to vibrate. Mechanical waves are produced when a source of energy causes a medium to vibrate. AKA, A disturbance! AKA, A disturbance!

21. Types of Mechanical Waves There are two kinds: There are two kinds: 1.Transverse 2.Longitudinal Rope exercise.

22. Transverse Waves Properties of a transverse wave Properties of a transverse wave

23. Wave Properties 1. Amplitude 2. Wave Length 3. Frequency 4. Speed

24. Wave Properties Amplitude, wavelength, frequency, speed

25. Amplitude A measure of how high the crest is from rest position A measure of how high the crest is from rest position Or a measure of the intensity of the compression Or a measure of the intensity of the compression

26. Wavelength The distance from crest to crest, or trough to trough The distance from crest to crest, or trough to trough

27. Wavelength Or from the center of one compression or rarefaction to the center of the next compression or rarefaction Or from the center of one compression or rarefaction to the center of the next compression or rarefaction

28. Frequency and Speed Frequency: Frequency: –How many waves pass a point in a given amount of time. –Example: on the beach you may average 3 waves each minute. What’s the waves frequency?

29. Speed Speed – How fast the wave is moving. Speed – How fast the wave is moving. It is closely related to frequency It is closely related to frequency

30. Longitudinal Waves Also known as compression waves Also known as compression waves Slinky exercise Slinky exercise

31. Longitudinal Waves Properties of longitudinal waves. Properties of longitudinal waves.

32. Longitudinal Waves Parts of longitudinal waves. Parts of longitudinal waves. –Compression –Rarefaction

33. Wave Speed To calculate wave speed you need to know 1. 1.Wavelength (distance between waves) a) a) Measured in Meters (m) 2. 2.Wave Period (time it takes for two crests to pass a particular point a) a) Measured in Seconds (s) 3. 3.OR Wave Frequency (# waves that pass a point in a given amount of time.) Speed= distance/time (S=d/t) so… S= wavelength /period OR S= (wavelength)(Frequency)

34. Try One A wave has a frequency of 3 waves per second. What is its speed if its wave length is 3 meters? A wave has a frequency of 3 waves per second. What is its speed if its wave length is 3 meters? 4 waves pass a fixed point in 2 seconds. If the wave has a wave length of 3 meters, what is its speed? 4 waves pass a fixed point in 2 seconds. If the wave has a wave length of 3 meters, what is its speed?

35. Electromagnetic Waves Do not need a medium Do not need a medium Examples: X-Rays, Gamma Rays, Microwaves, Light Waves, and Radio Waves. Examples: X-Rays, Gamma Rays, Microwaves, Light Waves, and Radio Waves.