Question

When a ray of light goes from a denser into a rarer medium.

• A. The wavelength of light is decreased
• B. The frequency of light is increased
• C. The speed of light is increased
• D. The light undergoes a phase change of $\pi$

Answer 1

Answer: (C)

The speed of light is increased

When a wave goes from a denser into a rarer medium, its speed increases. Since frequency $n$ does not change, the wavelength $\lambda =v/n$ increases. There is no phase change on refraction. Hence the correct choice is (c).