The light rays from the sun consist of seven different colors – red, orange, yellow, green, blue, indigo and violet (ROYGBIV). We see seven different colors when these sun are passed through a glass prism.
The splitting of a ray into its component colors is known as dispersion of light. The band of colors into which the light splits is known as a spectrum. White light consists of photons of various wavelengths (or colors). Photons of different wavelength travel with different speed. The red photon has the longest wavelength and the violet photon has the shortest wavelength. Thus when a white light passes through a prism, different photons cross the medium at different speeds and deviating by different angles. The red color appears at the top of the spectrum because it is bent the least or it is refracted the least.. On the other hand, the violet end of the spectrum is bent the most or refracted most, as it takes longer to traverse the glass medium.
When two prisms are placed with their vertices and bases in the opposite direction, the spectrum of seven colors from the first prism enters the second prism and only a white light comes out.
The most familiar example of dispersion is a rainbow which is seen when the sun appears in the sky after the rains. The moisture in the atmosphere behaves like tiny prisms, dispersing the sun’s rays into seven colors.
We see only the colors which are reflected. For example a leaf looks green in the sun, because it absorbs all the other six colors from the sun’s rays and reflects the green photons of the spectrum. These green photons reach our eyes and give us a sensation that the leaf is green in color. Similarly, an object looks black because the entire spectrum of light is absorbed by the black object, hence it looks black. When an object seems white it means that it is reflecting all the light back and is not absorbing any photons of the seven colors. Any color that we see other than the seven colors are actually a combinations of two or more of the seven colors of the spectrum. This is the reason we wear dark colors in winter so that it absorbs all the light falling on it and hence keep us warm. In summer season, we wear white or light colored clothes because we do not want the clothes to absorb sun light.
Image sources:
https://www.educationalelectronicsusa.com/p/images/light-XVa.gif
https://www.educationalelectronicsusa.com/p/images/light-XVb.gif
https://2.bp.blogspot.com/-bRkzX7j9RDE/Tu_PXKG85rI/AAAAAAAAAVc/pbC2WgCChHs/s1600/rainbow.png
SchoolTutoring Academy is the premier educational services company for K-12 and college students. We offer tutoring programs for students in K-12, AP classesand college. We cover a variety of subjects in including physics tutoring. To learn more about how we help parents and students in Newark Linda visit: Tutoring in Newark.