Wave

4. The specific direction that a transverse wave is vibrating.
5. The particles of the medium move ________ to the direction of which the wave is traveling.
8. The parts of a longitudinal wave that are spread apart.
9. When a wave changes direction because it goes into a new medium.
11. A disturbance in matter that carries energy from one place to another.
13. A type of wave where the medium moves parallel (horizontal) to the direction the energy is moving. Sound is this type of wave.
15. The material a mechanical wave moves through.
16. A single disturbance that moves from point to point through a medium is called a ___.
17. When waves spread out to fill the space through which they are moving.
20. A repeated back and forth or up and down motion that gives energy to a wave. Also called "oscillation".

1. Photons are particles which transmit___.
2. The parts of a longitudinal wave that are closest together.
3. A transverse wave of pure energy that can go through both a medium and empty space (vacuum). Light is this kind of wave.
6. A disturbance that transfers energy from place to place
7. The lowest point of a transverse wave.
10. The maximum distance from the rest position that the medium moves in a wave.
12. The distance between two similar parts of a wave.
14. A type of wave where the medium moves perpendicular (vertical) to the direction the energy is moving.
18. The number of cycles of a periodic wave occurring per unit time is defined as a wave's ____.
19. The SI unit for frequency is ___.
20. Totally empty space (no medium). Sound cannot travel through this.