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Wave Properties Unit 30
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Page 1: Unit 30 Wave Properties

Wave Properties

Unit 30

Page 2: Unit 30 Wave Properties

Mechanical Waves

• Waves are a disturbance that transfers energy from one molecule to another across space.

• A medium is the matter that waves travel through.

• It can be water, air, or even solids.

Page 3: Unit 30 Wave Properties

Types of Mechanical Waves

• There are three types of mechanical waves:– Surface Waves

– Longitudinal Waves

– Transverse Waves

Page 4: Unit 30 Wave Properties

Types of Waves

• Surface Waves– Surface waves travel along the surface

of two separating mediums.– Particles at the surface of a surface

wave will rotate in a clockwise manner.

• See the blue particle below.

Page 5: Unit 30 Wave Properties

Types of Waves• Surface Waves

– If you are swimming in the ocean and a large wave comes by, it does not push you forward, you simply rise up and down as it passes!

Page 6: Unit 30 Wave Properties

Types of Waves Con’t

• Longitudinal Waves– Waves that move in

the same direction as the disturbance in the medium

– 2 main parts• Compression• Rarefaction

Page 7: Unit 30 Wave Properties

Tsunamis • Tsunamis show the effects of

longitudinal waves when they retract and then advance.

• Often a tsunami is preceeded by a retraction of the water before the wall arrives

Here you can see the water drawback (trough) exposing these rocks, with the

incoming tsunami in the distance

Now the crest arrives, sending a wall of water onto the shore.

Page 8: Unit 30 Wave Properties

Types of Waves con’t• Transverse Waves

– Any wave in which the medium moves at right angles to the direction of the wave.

– 2 main parts• Crest (the highest point of the wave)• Trough (the lowest point of the wave)

Page 9: Unit 30 Wave Properties

Wave Properties

Page 10: Unit 30 Wave Properties

Frequency

• Frequency– The number of waves that

pass a point in a given amount of time.

– Hertz• The unit used to measure

the frequency.• 1 Hz = 1 cycle/sec

– Frequency is the reciprocal of the period.

• Freq. = 1 / Period

Page 11: Unit 30 Wave Properties

Period

• Period– The period of a wave

represents the time it takes one wave to pass.

– The period is the opposite of the frequency.

• Period = 1 / Freq.

Page 12: Unit 30 Wave Properties

Wavelength

• Wavelength– Wavelength is measured from two

identical points on wave.– Usually measured from crest to crest or

trough to trough

Page 13: Unit 30 Wave Properties

Wave Speed

• Speed – How fast or slow the wave is moving.

Formula:Speed = Frequency x Wavelength

*If the speed of a wave is held constant, then as the frequency goes up, the wavelength goes down.

Page 14: Unit 30 Wave Properties

Wave Speed Continued

• Wave speed is affected by the medium

• Waves can travel 770 mph in air (Speed of Sound)

• But, 2-4 miles per second in solids (10000 mph speed of earthquake)

Page 15: Unit 30 Wave Properties

Earthquakes• An earthquake is very similar to

sound waves or waves in water.• It is a disturbance in the Earth that

causes a wave to travel through the solids.

• They are known as seismic waves.

Page 16: Unit 30 Wave Properties

Amplitude

• Amplitude– The vertical distance between the line of origin and

the crest or trough.

– The more energy a wave has then the greater the amplitude (think of an amplifier in a stereo).

Page 18: Unit 30 Wave Properties

Reflection• Reflection

– When a wave bounces off of a surface.

The angle the wave comes in at is equal to the angle the wave goes out at.

Page 19: Unit 30 Wave Properties

Refraction

• Refraction– The bending of light as a

result of a change in speed.

– The wave will slow down when going from a less dense medium to a more dense medium.

Page 20: Unit 30 Wave Properties

Interference

• Interference– Constructive

• Produces one larger wave

– Destructive• Produces a smaller wave or no wave at

all.The green wave in the diagram above and to the left has combined the read and blue waves.

Page 21: Unit 30 Wave Properties

Diffraction

• Diffraction is the bending of a wave as it passes through an opening or around an object.