Question

A beam of white light undergoes dispersion through a triangular glass prism forming a band of seven colours. Which of the statements is/are correct?

1. a) The red-coloured component has minimum refractive index.
2. (b) The violet-coloured component deviates the least.
3. (c) All components of white light have same speed in glass.

• A. 2 only
• B. 1, 3
• C. 1 only
• D. 2, 3

Answer 1

Answer:

C. 1 only

• The red-coloured component has minimum refractive index.This is because the refractive index of a material is wavelength-dependent (dispersion).

• The refractive index is inversely proportional to the wavelength of light.

• Since red light has the longest wavelength in the visible spectrum, it experiences the least bending (refraction) when entering or leaving a medium.

• Consequently, it has the lowest refractive index compared to other colors like violet, which has the shortest wavelength and the highest refractive index.

• This phenomenon is responsible for the separation of white light into its constituent colors when it passes through a prism.