waves

4. a lens that is curved inwards
5. unit of frquency
7. allowing light to come through imperfectly
10. narrow beams of light
13. invisble radiation simular to light but with a slightly higher frequency and more energy
15. wide stream of light rays, all moving in the same direction
16. high energy electromagnetic radiation produced during nuclear reactions
19. invisible radiation emmited by all warm objects

1. a unit of measurement of relative sound intensity
2. change in the speed of light as it passes from one substance into another
3. a lens that is curved outwards
6. transmitter of energy without the movement of particles from place to place
7. describes a substance that allows most light to pass through it
8. reigion in which the particles are closer than when not disturbed by a wave
9. wave involving the vibration of particles perpendicular to the direction of energy tranfer
11. maximum distance that a particle moves away from its undisturbed position
12. describes a substance that does not allow any light to pass through it
14. bouncing off the surface of a substance
17. material through which a wave moves
18. high energy electromagnetic waves that can be transmitted through solids and provide information about their structure