What happens when a light ray is incident normally to the interface of two media?

When a light ray is incident normally (or perpendicularly) to the interface of two media, it continues to travel in a straight line into the second medium without any deviation. This is because the angle of incidence is 0 degrees, and according to Snell's Law (which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant), when the angle of incidence is 0, the angle of refraction is also 0.

However, the speed and wavelength of the light may change as it enters the second medium, depending on the refractive indices of the two media. If the second medium has a higher refractive index (is optically denser) than the first, the light will slow down and its wavelength will decrease. If the second medium has a lower refractive index (is optically rarer) than the first, the light will speed up and its wavelength will increase.

Despite these changes in speed and wavelength, the frequency of the light remains constant as it passes from one medium to another, as frequency is a property of the source of the light and is