Question

When a ray of light enters a glass slab from air

• A. its wavelength decreases
• B. its wavelength increases
• C. its frequency increases
• D. neither its wavelength not its frequency changes

Answer 1

The correct option is A its wavelength decreases

On entering a glass slab the velocity decreases. $v=\nu \lambda$

Frequency is inherent property of a wave and does not change. So the wavelength decreses which results in reduction in velocity on entering a glass slab from air.

Answer) A. its wavelength decreases.