Slide 1

Slide 2

Waves There are two kinds of motion: Harmonic motion- Movement that repeats over and over again. Linear motion- Moving from one place to another (We have learned much about this) Waves are a type of harmonic motion

Slide 3

Terms to describe waves: Cycle: The motion from beginning to end before it begins repeating. Period (T): The time it takes to complete one cycle. Metric SI Unit: (s) seconds Frequency (f): The number of cycles that occurs in a second. Metric SI Unit: (Hz) Hertz or (s -1 ) inverse seconds Amplitude: How big the wave is or how far away from its origin it is. Unit depends on the kind of wave.

Slide 4

Parts of a wave Crest: The highest point of the wave Trough: the lowest point of the wave Wavelength ( ): The distance between two crests or two troughs Amplitude: How far the wave is from the origin

Slide 5

Sound vs. Light Light waves move up and down and we call them Transverse waves. That means the wave moves perpendicular to the direction it is traveling.

Slide 6

Sound Waves move back and forth. They are called Longitudinal. That means the wave moves parallel to the direction it is traveling.

Slide 7

Sometimes waves are named by how they are created. Light is made from Electromagnetic radiation and is called an Electromagnetic wave. Sound is made from matter squeezing together or stretching apart and is called a Compressional wave.

Slide 8

Both waves have the same parts; they just look a little different. Rarefaction: Where the wave density is smallest Compression: Where the density is the largest Crest Trough Different names are given to the corresponding parts

Slide 9

Because a compression wave depends on the different density of something, it needs a medium. A medium is the stuff that the compressional wave travels in. If you screamed on the moon, would you be heard? Electromagnetic radiation (light) does not need a medium to travel. Thankfully, otherwise the earth would be pretty dark.

Slide 10

Doppler Effect Doppler effect happens as objects making sound move past a stationary observer. The police car siren sounds higher pitched as it is approaching and lower pitched when it is driving away. Remember: a shorter wavelength will give a higher frequency and a higher frequency of sound has a higher pitch.

Slide 11

The waves of sound are heard as squeezing together as they approach and stretched as they leave.

Slide 12

How are waves analyzed? Some waves can travel at different speeds. The velocity of the wave can be calculated using the following formula: Ex: Light travels at a constant speed in a vacuum and its velocity is given the symbol (c). The speed of light is c = 2.99x 10 8 m/s 299,000,000 meters/second

Slide 13

Waves carry Energy The higher the frequency the higher the energy. f = E The longer the wavelength the lower the energy. = E

Slide 14

Waves can move a variety of ways Reflection: The wave can bounce off and go in a new direction. Refraction: The wave slows down when it passes through a medium that is more dense and it bends

Slide 15

Diffraction: How light and sound can bend around corners and as they pass through holes Absorption: The wave can be absorbed by a material and disappear.

Slide 16

Waves can also interact with each other We call this interference and there are two kinds of interference: This happens when the crest of one wave overlaps with the crest of another wave. The new wave becomes bigger or has more amplitude.

Slide 17

Destructive interference is when the crest of one wave overlaps the trough of another wave and the new wave is smaller or has less amplitude.

Slide 18

What would interference between these pairs of waves look like? Is it constructive or destructive interference?