Question

What do you mean by dispersion of light?

Answer 1

Hint: When the white light passes through some transparent material such as glass prism, it splits into its seven constituent colors. The white light consists of seven different colors (colors of rainbow). Rainbow forms due to dispersion of light.

Complete answer:
We know that the white light consists of seven different colors. When the white light passes through some transparent material such as glass prism, it splits into its seven constituent colors. This phenomenon of splitting of white light is known as dispersion of light.
 We will study the cause of dispersion of light. The main cause of dispersion of light is due to the extent of refraction of light for each constituent color of white light. We know that the speed of light remains constant in the vacuum but it changes when the light passes through different materials of different refractive index. The angle of deviation is more for the maximum refractive index of the medium for different colors.
We know the refractive index of the medium is the ratio of speed of light in vacuum to the speed of light in the given medium. Therefore, we can see that the color whose speed is greater will have a smaller refractive index. We know that the speed of violet light is lower as compared to the speed of red light. Therefore, we can see that the violet color has the maximum refractive index and therefore, it will deviate the most as compared to the red color.

Note:To answer this question, the key is to remember the formula for refractive index in terms of speed of light in a given medium. Remember, dispersion and refraction are two different concepts. Note that the refractive index is inversely proportional to the wavelength of light.