Question

What happens to a light wave when it goes from something less dense to more dense?

1) The wave speeds up
2) The speed of the wave doesn't change
3) The wave slows down

Answer 1

A light wave slows down and refracts towards the normal when it passes from a less dense to a denser medium, resulting in a decrease in wavelength, but the frequency remains unchanged.

Step-by-step explanation:

When a light wave travels from a less dense medium to a more dense medium, the wave slows down. This is because light changes speed when it enters a different medium. When light slows down, its path bends due to refraction. Additionally, the wavelength of the light wave decreases, but its frequency remains unchanged since the speed of light can only change due to a medium, not because of motion in space. Thus, when transitioning into a denser medium, like glass, light refracts towards the normal, and its speed and wavelength decrease correspondingly.