What is prism?
A prism is an object made up of a transparent material, like glass or plastic that has at least two flat surfaces that from an acute angle (less than 90O degrees).
We have seen that white light is made of different colors and we can split white light. Is it possible to do the reverse? That is, can you get white color by mixing colors? Try this activity.
You need oil pastel and white paper. Take different oil pastel colors. Choose colors which are exactly seen on the rainbow. Apply colors over each other on a white paper. Did you get white color?
Let’s make a rainbow
You must surely have seen a rainbow in the sky. Why don’t you try making one at your class room?
Place a flat but deep pan. Place this pan where there is direct sunlight. Place a plain mirror in the pan as shown in the diagram, so that you see sunlight reflected on you ceiling or on a white wall. Next slowly pour water in to the pan. At particular level of water, you will get a beautiful rainbow colors on the wall. If the colors are not clear adjust the position of the mirror to bring it into focus. This arrangement of colors in sunlight is called spectrum.
Why danger lights in vehicles are red in colour?
1. Red color is scattered the least by air molecules.
2. Red color has the highest wavelength of all the other colors. So red color is able to travel the longest distance through air, fog.
When white light is passed through a prism as shown in the figure, the colors of the rainbow emerge from the prism