1. Waves

2. The time it takes for one wavelength to pass is called the period. The number of wavelengths passing at a given time is called frequency.

3. Waves Sound travels in a wave. The wave is caused by air particles vibrating back and forth.

4. Waves When the source of sound moves, it creates a Doppler Effect. Notice how the waves are more compressed at the front of the truck then behind it.

5. Waves This change in the compression of the waves changes the sound of vehicle as it drives by.

6. Waves Light also has characteristics of a wave.

7. Waves The Doppler Effect of light is how we study our galaxy in relation to other ones in the known universe. Light has a Doppler Effect just like sound.

8. Waves When the source of light is moving away from the observer it is called the red shift. When the source of light is moving toward the observer it is called the blue shift.