1. Source of waves All types of waves are formed from something vibrating An object that vibrates in a very regular way is said to be in “simple harmonic motion” These simple harmonic motions are part of nature and are described in math by sine wavessine waves

2. Waves do one thing Waves transfer energy without transferring the matter of the media Even ocean waves in the open sea don’t move any water (for the most part) they only move up and down.

3. Waves come in two flavors Media/medium-the matter which a wave passes through. What does a psychic medium do? Mechanical Wave - a wave that needs a medium to travel through Electromagnetic Wave– a wave that does not need a medium to travel through We will talk about these a lot…………..but not now.

4. Mechanical waves come in 2 flavors Transverse- a mechanical wave where the mediums displacement is perpendicular to the movement (propagation) of the wave Longitudinal (compression)- a mechanical wave where the displacement of the medium is parallel the movement (propagation) of the wave – Compression—positive amplitude – Rarefaction– negative amplitude

5. Mechanical waves come in 2 flavors Transverse- applet Transverse- Longitudinal (compression)- applet Longitudinal

6. Wave Parts Transverse and Longitudinal waves have the same parts, but they are easier to see in a transverse wave. Wavelength – distance between identical parts on two adjacent wave forms

7. Wave Parts Amplitude- Displacement from the undisturbed location at a given point in a wave form. There is a positive and negative

8. Wave Parts Crest – Maximum positive amplitude of a wave form Trough– Minimum negative amplitude of a wave form.

9. Pulses A pulse is ½ of an full wave. It can be positive or negative What does positive or negative mean for a longitudinal wave? A full wave cycle is called an oscillation

10. Wave Measurements Amplitude of a wave– measured in many different ways, from pressure to meters, don’t worry too much about this, we won’t be using it to do any math. Cycle/Oscillation- one complete motion of a wave. Wavelength (λ)—is measured in a unit of length, for us that will be meters (m)

11. Wave Measurements Frequency (f) —is the number of times an identical part of a series of waves passes a given point during a unit of time. Usually measured in cycles per second. – 1 cycle/second = 1 Hertz (Hz) Period (T) – the period of a wave is the time it takes to complete one oscillation, measured in time, for us it is usually seconds (s) f = 1/T

12. Speed of Waves In the slinky lab, where you able to make a wave travel faster in the slinky? The speed of a wave is determined by “characteristics” of the medium Transverse wave appletapplet The speed of waves can be related to frequency and wavelength as follows: ν=λfν=λf

13. Let’s use v=fλ NOAA (National Oceanic and Atmospheric administration) uses buoys to monitor ocean activity. If the distance between two buoys is 100m and there are 15 crests, what is the λ? If the buoy is bobbing up and down 12 times every minute, what is the frequency of the waves in Hz? How fast are the waves moving? What is the period of a wave? λ=6.66m f= 0.2Hz v= 1.33m/s T = 5s

14. Reflections I regret not going to my dad’s 50 th birthday party I wish I had studied abroad When waves propagate into a new material it is called the intersection is called a boundary When waves meet an immovable surface the waves tend to bounce off or reflect. There are two types of boundariesboundaries – A free boundary- the wave reflects with the same amplitude – A fixed boundary- The wave reflects with the opposite amplitude

15. Interference 2 or more waves traveling in the same medium can interfere with each other, this takes two forms Constructive interference – when two waves meet at a point and the amplitude of the combined wave increases. Constructive interference Destructive interference – when two waves meet at a point and the amplitude of the combined wave decreases. Destructive interference

16. Standing waves A standing wave or stationary wave results from the constructive/destructive interference of a wave which reflects back through a medium. A standing wave This is often the case in nature, such as a string on a guitar.

17. Diffraction Waves have a tendency to bend around the edge of an object. They do this when the hit an obstacle, an opening, or an edge This phenomena is called diffraction

18. Diffraction Ripple tank appletapplet

19. Real Waves Big Wave Surfing