Question

which properties of light remain constant during refraction

Answer 1

At an interface the total energy must add up and this requires the frequency to remain constant outside and inside the medium. On the other hand the wavelength ,lamda, depends on the speed of light in the medium and is reduced by the index of refraction

Answer 2

Frequency is constant during refraction

bcoz wave must be connected at the

boundary, so the up and down variations

must match each other on each side,

hence the fundamental frequency must be

the same. This answer is more intuitive and

easier to visualize. The case of light is not

really up and down motion, so I say that

figuratively. However, the field variations

must match in particular ways at the

boundary