2021 · Q18
When a white light beam is made to fall on a hollow prism filled with water, it breaks into seven constituent colours. Which of the following colours suffers the maximum angle of deviation?
general-sciencephysics-light-electricity
- ARed
- BViolet
- CGreen
- DAll suffer by equal amount of deviation
Explanation
When white light passes through a prism, each colour deviates by a different angle because the refractive index of the medium varies with wavelength — it is highest for the shortest wavelength. Violet light has the shortest wavelength among the seven colours and therefore suffers the maximum angle of deviation, while red deviates the least. A water-filled hollow prism disperses light the same way. Hence violet deviates most.