1. Waves 7th Grade Science

2. Types of Waves Electromagnetic Waves: Do not require a medium to move
Matter Waves: Produced by electrons and particles
Mechanical: Requires a medium to travel (air, water, rope)
A. Transverse: Move perpendicular to direction of the wave.
Longitudinal: Move parallel to direction of the wave.
Surface: Both transverse and longitudinal mixed together

3. Transverse Examples: Radio, Heat, and Light

4. Longitudinal (Compression) Sound Waves

5. Surface Waves Water

6. Parts of a Wave
Use your green packet to define the parts of a wave. Amplitude: Wavelength: Frequency: Speed:

7. Parts of a Wave
Check your definitions Amplitude: The maximum distance the medium vibrates in a medium. (Crest to Trough) Wavelength: The distance between one crest and the next or from trough to the next trough Frequency: The number of times waves pass a point in a certain amount of time Speed: Different waves travel at different speeds

8. Changing Direction of Waves
Reflection: A wave cannot pass through a medium, instead it bounces back
Ex. Mirror

9. Changing Direction of Waves
Refraction: When one area of a wave changes direction before another area.
Ex. Straw in cup

10. Changing Direction of Waves
Diffraction: When waves move/bend around a barrier
See video