Light waves travel from the air into a lens made of glass. Their velocity decreases as they enter the glass. How does this affect the frequency and wavelength of the light waves!

Frequency decreases

Wavelength increases

Explanation:

Frequency is how often a wave occurs. Wavelength is how long a wave is.

Waves that travel fast have a high frequency and short wavelength.

When they slow down, they have a lower frequency and longer wavelength.

Think about the electromagnetic spectrum: Gamma rays are fast, with high frequencies and short wavelengths (look bunched together). Radiowaves are slow, with low frequencies and long wavelengths (look stretched out).