The light

2. The point on a wave with the greatest positive value or upward displacement within a cycle.
3. A natural or artificial process that emits a visible electromagnetic radiation.
6. The point on the medium that exhibits the maximum amount of negative or downward displacement from the rest position.
8. The repeated or regular way in which something happens or is done.
10. It is the line perpendicular to the boundary passing through the point of incidence.
14. The way in which the energy of a photon is taken up by matter, typically by the electrons of an atom, transforming that into internal energy.
15. A change in the observed frequency of a wave.
16. It's the change of direction of a ray or a wave after bumping into a barrier or a surface.
18. It's the magnitude, thus a scalar quantity, of the rate of change of an object's position.
19. It's space devoid of matter.
20. The electromagnetic radiation within a certain portion of the electromagnetic spectrum.

1. It is a transparent optical element with flat and polished surfaces and it is mostly used to disperse light.
4. An attribute of things that result from the light they reflect, transmit or emit in so far as this light causes a visual sensation that depends on its wavelenght.
5. The distance travelled by a wave in a specified context.
7. Imaginary surface representing corresponding points of a wave that vibrates in unison.
9. To be permeable to electromagnetic radiations of specified frequences as to visible light or radio waves.
11. It refers to the maximum displacement of a particle of a medium from its rest position when a wave passes through it.
12. Reflection of waves or particles from a surface such that the incident rays on the surface are scattered at many angles rather than at just one angle.
13. Line that marks the limits or edges of something and separates it from other things or places. So it is a dividing line between mediums.
17. A small breach on a surface; if its size is equatable with the wavelength of a wave which is passing through, it might give rise to a diffraction.