What happens to the speed of light when it enters a medium with a higher refractive index?

What happens to the speed of light when it enters a medium with a higher refractive index?

• A. It Becomes Infinite
• B. It Increases
• C. It Remains the Same
• D. It Decreases

Answer: (D)

The main idea is that light travels at a speed set by the medium it’s moving through. The speed in a medium is given by v = c/n, where c is the speed of light in vacuum and n is the refractive index. A higher refractive index means a larger division by n, so the speed v becomes smaller. When light enters a medium with a higher n, it slows down. The frequency stays the same across the boundary, so the wavelength inside the denser medium becomes shorter (λ = v/f). So the correct answer is that the speed decreases.

The main idea is that light travels at a speed set by the medium it’s moving through. The speed in a medium is given by v = c/n, where c is the speed of light in vacuum and n is the refractive index. A higher refractive index means a larger division by n, so the speed v becomes smaller. When light enters a medium with a higher n, it slows down. The frequency stays the same across the boundary, so the wavelength inside the denser medium becomes shorter (λ = v/f). So the correct answer is that the speed decreases.