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 nor its frequency changes

Answer 1

Answer: (A)

its wavelength decreases

Answer 2

$\lambda=\frac{v}{f}$
In moving from air to glass, / remains unchanged while v
decreases. Hence, $\lambda$ should decrease.