Question

In glass, the violet light travels faster than red light. Is the statement true?

Answer 1

Hint:We know that when the light travels from the glass, it will travel from atom to atom at the vacuum speed. This speed will be lowered by the absorption and re-emission of light when it will travel from atom to atom. The speed of light in any medium will depend on the wavelength of the light.

Complete answer:
As we know that when a light is passed through prism, it gets split into a spectrum of seven colors. Also, the speed of light will be different when it will travel in glass than when it will travel in air. This means that the velocity of all the colors will be the same, but the frequency and the wavelength of the different colors will be different.

Also, we know that the refractive index of the medium is inversely proportional to the speed of light. Therefore, by the refractive index formula, the wavelength of light is directly proportional the speed of light in the medium. This means that the greater the wavelength of light, greater will be the speed of light.As we know that, the wavelength of red light is greater than the wavelength of violet light. Therefore, the speed of red light will be greater than the violet.

Therefore, in glass the red light will travel faster than the violet light. Hence, this statement is not true.

Note:If we talk about speed of light in terms of refractive index of material, we can say that when the refractive index is high, the speed of light will be low. On the other hand, when the refractive index of the material will be low, the speed of light will be high. This is because the refractive index will be different for different parts of the spectrum.