Some interesting facts about light

Rainbow

Rainbow is arch formed by light refracted by drops of water diffused in the air. You can see it when you have sun behind your back and you look at the rain. In the brightest or primary bow, often the only one seen, the colors are arranged with the red outside. Above the perfect bow is a secondary bow, in which the colors are arranged in reverse order; this bow is dimmer, because of a double reflection within the drops. When the sunlight enters a raindrop it is refracted, or bent, by and reflected from the drop in such a way that the light appears as a spectrum of colors. The colors can be seen, however, only when the angle of reflection between the sun, the drop of water, and the observer's line of vision is between 40° and 42°. When the sun is low in the sky the rainbow appears relatively high; as the sun rises higher, the rainbow appears lower in the sky, maintaining the critical 40°- to 42°-angle. When the sun is more than 42° above the horizon no rainbow can be seen.

Your own rainbow

You can easily produce rainbow in your room. Take flat container, pour some water in it and place a mirror in the water (mirror has to be partly in the water, partly out of the water). Now place the container in front of the window that the part of mirror (one of of the water) reflects sunlight towards the wall. You can see a small rainbow on the wall under the reflected white light.
Figure 1 Your rainbow on the wall
Figure 2 Beautiful rainbow in the sky

Fire

When you look at a fire you can see how atoms of gases give out light. But when you look carefuly you notice small dark line between wood and the flame . It's dark because gases are not hot enough to burn. They become hot later, burn and emit light.

Colors

Have you ever wondered why different materials have different colors? Light to be reflected by the object is first absorbed by the object and then reemitted. When light is absorbed its energy can be almost fully reemited (the object is then white) or can be changed into kinetic energy of atoms of material. Color of material depends on the part of energy it changes into kinetic energy of its atoms (when all energy is changed the object is black) and which part of the spectrum is absorbed (white light consists of lights of different colors). When kinetic energy of atoms rises - material gets warmer, that's why black materials get hot quickly, white slowly.
White materials reflect all light they receive
Yellow materials absorb blue light and reflect rest of light
Light blue materials absorb red light and reflect rest of light
Purple materials absorb green light and reflect rest of light
Black materials absorb all light they receive