What happens to waves when they enter a new medium, according to Snell's Law?

When waves enter a new medium, they indeed change direction based on their angle of incidence, which is precisely what Snell's Law describes. Snell's Law states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant and is related to the speeds of light in the two media. This results in the bending of waves when they cross into a different medium, such as light moving from air into water.

For example, if a wave travels from air (less dense) to water (more dense), it slows down and bends toward the normal line (the imaginary line perpendicular to the interface between the two media). Conversely, when waves move from a more dense medium to a less dense medium, they bend away from the normal.

Understanding this principle illustrates how the speed of the wave changes with the properties of the two different media while the frequency remains constant. Thus, changing direction (refraction) is the key effect that occurs in accordance with Snell's Law when waves transition between different media.