Waves

3. Bouncing off the surface of a substances
4. Invisible readiation emitted by all warm objects, you feel it as heat
6. Narrow beams of light
7. Lens curved inwards
8. Region in which the particles are closer than when not disturbed by a wave
9. Allowing light to come though imperfectly, as in frosted glass
11. Material though which a wave moves
13. Describes a substance that does not allow any light to pass though it
14. Describes a substance that allows most light to pass through it,objects can be seen clearly through transparent substances
16. Maximum distance that a particle moves away from its undisturbed position
17. High energy electromagnetic radiaton produced doing nuclear reactions
18. Unit of frequency; its abbreviation is Hz, one hertz is equal to one vibration every second
19. A unit of measurement of relative sound intensity

1. Lens curved outwards
2. Change in the speed of light as it passes from one substance into another, it usually involves a change in direction
5. Region in which the particles are farther apart than when not disturbed by a wave
10. Wave involving the vibration of particles perpendicular to the direction of energy transverse.
12. Sound with frequencies too high for humans to hear
15. Transmitter of energy without the movment of particles from place to place, the vibration of particles or energy fields is involved
20. Wide stream of light rays