Question

Assertion (A): The splitting up of white light into seven colours on passing through a transparent medium like a triangular glass prism is called dispersion of light.

Reason (R): The rainbow is an arch of seven colours visible in the sky which is produced by the dispersion of sun’s light by the tiny raindrops in the atmosphere.

Options

• Both A and R are true and R is correct explanation of the assertion.

• Both A and R are true but R is not the correct explanation of the assertion.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true but R is not the correct explanation of the assertion.

Explanation:

The assertion is true because the breakdown of white light into its seven component colours when passing through a triangular prism accurately defines the phenomenon of dispersion. The reason is also true because a rainbow is a natural manifestation of dispersion caused by atmospheric raindrops acting like tiny prisms. However, the reason is not the correct explanation for the assertion because it merely provides a real-world example of dispersion (the rainbow) rather than explaining the underlying physical cause of why light splits inside a prism (which is due to different colours of light travelling at different speeds in a medium).