Question

What happens to the wavelength of light as it passes from water to air?
Responses
A It decreases.It decreases.
B It increases.It increases.
C It doubles.It doubles.
D It stays the same.

Answer 1

B — It increases.

Explanation: Frequency stays the same when light crosses the boundary, but its speed increases going from water (n ≈ 1.33) to air (n ≈ 1). Since wavelength λ = v/f, the increase in speed means the wavelength increases (by about the factor n_water/n_air ≈ 1.33).