This described situation is known as Refraction.
Refraction is a phenomenon in which the light bends or changes it direction when passing through a medium with a refractive index [tex]n[/tex] different from the other medium.
[tex]n=\frac{c}{v}[/tex]
Being [tex]n[/tex] a relation between the speed of light in vacuum and its speed in the other medium. This means the speed of propagation does change.
The wavelength may be modified because it depends on the medium.
Nevertheless, in this process the refracted ray of light does not change its frequency [tex]f[/tex], because frequency is:
[tex]f=\frac{1}{T}[/tex]
Where [tex]T[/tex] is the period of the wave and this remains unchanged, hence the frequency, as well.
