Waves

1. The unit for frequency.
3. A substance or material that carries a wave.
6. When a wave travels through a medium.
7. Reflection from a rough surface that causes scattering.
11. The distance from a point on one wave to the equivalent point on the adjacent wave.
12. Reflection from a smooth surface, parallel incident rays will all bounce off in a single direction.
14. A wave is the transfer of energy through a medium or a vacuum, without any transfer of the medium itself.
16. An image that is turned upside-down from the original object.
19. A wave with oscillations perpendicular to the direction of energy transfer, e.g. electromagnetic waves.
21. A filter that absorbs certain wavelengths of visible light and transmits other wavelengths.
22. The repeated back-and-forth motion of a particle or object about its equilibrium (undisturbed) position.
23. The maximum displacement of a point on a wave away from its undisturbed position.
24. A simple camera without a lens but with a tiny aperture.
25. The process of receiving or taking in.
26. A wave with oscillations parallel to the direction of energy transfer, e.g. sound waves.
29. The change in direction of a wave due to the change in velocity when moving from one medium to another.

2. The act of a wave bouncing back at the boundary of a medium.
4. A region of high pressure due to particles being close together.
5. When a wave has changed direction at the boundary between two different media.
8. A sound caused by the reflection of sound waves from a surface to the listener.
9. A region of low pressure in a longitudinal wave due to particles being spread further apart.
10. A universal physical constant that is approximately 300,000,000 m/s.
13. The membrane that separates the outer ear from the middle ear, it vibrates when sound waves reach it.
15. Sound waves that have a frequency higher than the upper limit of hearing for humans.
17. A line at right angles to a surface.
18. A lens that curves outwards so it is thicker in the middle than at the edges. It causes parallel rays of light to converge. The image produced can be real or virtual.
20. When two or more waves pass through the same point, the effect they have is added together.
25. The range of frequencies an organism can hear, in humans it is 20 Hz to 20,000 Hz.
27. The ability of the lens to alter its shape to allow objects to be seen clearly.
28. The number of waves or cycles passing a point each second.