hello, everyone.

We all know that electromagnetic waves travel more slowly in a transparent medium than in a vacuum.

Their frequency stays the same but their wavelength gets less.

v=f X lambda

My question is why "their frequency stays the same but their wavelength gets less."  ???

Can it be that the wavelength stays the same but their frequency gets less?

In that case, the velocity still decreases.

Are there any simulations to show that the frequency stays the same and the wavelength decreases when light enters glass from air?

Remember frequency has the element of time.

Thanks.