How many times will the red wavelength change during the transition from vacuum to glass

How many times will the red wavelength change during the transition from vacuum to glass, if the refractive index of the glass is 1.5?

Wavelength in vacuum: λ1 = s / ν, where the speed of light is s ≈ 3 * 108 m / s, v is the frequency of the vibrations of the red light wave.

Wavelength in glass: λ2 = s / (n * ν).

That is, during the transition from vacuum to glass, the vibration frequency will not change, but the vibration frequency will decrease n times.

Therefore, when passing from vacuum to glass, the wavelength will change in λ1 / λ2 = (c / v) * (n * v) / c = n = 1.5 times.

Answer: The wavelength of red will change by 1.5 times.