1. WAVES

2. Rhythmic disturbances that carry energy without carrying matter
What are Waves?
Rhythmic disturbances that carry energy without carrying matter

3. Types of Waves
Mechanical Waves – need matter (or medium) to transfer energy
A medium is the substance through which a wave can travel. Ex: air, water, particles, strings, solids, liquids, gases
Electromagnetic Waves – DO NOT NEED matter (or medium) to transfer energy
They do not need a medium, but they can go through matter, such as air, water, and glass

4. Mechanical waves can be transverse or longitudinal motion
Examples: Sound waves, ocean waves, ripples in water, earthquakes, wave of people at a sporting event

5. Some examples of Mechanical Waves

6. Electromagnetic Waves
Examples of electromagnetic waves: radiation, TV & radio waves, X-rays, microwaves, lasers, energy from the sun, visible light
All electromagnetic waves are transverse!

7. Transverse Waves
Transverse waves - energy moves perpendicular to direction of wave.
Examples: waves in water

8. Parts of a Transverse Wave
The crest is the highest point on a wave.

9. Parts of a Transverse Wave
The trough is the valley between two waves, is the lowest point.

10. Parts of a Transverse Wave
The wavelength is the horizontal distance, either between the crests or troughs of two consecutive waves.

11. Parts of a Transverse Wave
The amplitude is the distance from the undisturbed level to the trough or crest.

12. An ocean wave is an example of a mechanical transverse wave

14. A slinky is a good illustration of how a compressional wave moves
Longitudinal Wave
Matter in the medium moves forward and backward along the same direction that the wave travels.
Ex: Sound waves
A slinky is a good illustration of how a compressional wave moves

15. Parts of a Longitudinal Wave
The compression is the part of the wave where the particles are crowded together.

16. Parts of a Compressional Wave (Longitudinal)
The rarefaction is the part of the wave where the particles are spread apart.

17. Parts of a Compressional Wave (Longitudinal)
The wavelength is the distance from compression to compression or rarefaction to rarefaction.

18. Animation of Transverse and Longitudinal (Compression) Waves:

19. Waves BrainPOP Video

20. Energy and Waves
Frequency is expressed in hertz (Hz) which measures how many waves per second.
Higher frequency = more energy
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21. Shorter wavelength = more energy = higher frequency
Visible Light

22. Copy the top picture.

23. Amplitude- distance particles travel from the undisturbed position
Bigger amplitude = taller wave = more energy
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24. Sound