Light velocity, wavelength, and frequency

[JDiorio]

Just a quick concept check.

I was asked that as light travels between two media, what happens to its frequency, wavelength and velocity.

I want to say that the frequency remains the same while the velocity and wavelength change, based on the difference of the index of refraction between the two media. But because frequency remains constant, their changes are indirectly proportional so that the frequency stays the same.

Am i right? Thanks

 

[Doc Al]

You are right. Frequency remains the same.

 

[mikeph]

Can I ask why? I've never known. Does this way keep the electric field continuous or something?

 

[Doc Al]

Does this way keep the electric field continuous or something?

Exactly. The only way for the electric and magnetic fields to be continuous at the refractive boundary is if the frequency is unchanged.