First convert the wavelength to meters: λ = 3.835 × 10^−7 cm is 0.003835 in meters
The speed of light is: C = 3.0 × 10^8 m/s Frequency is the speed the wavelength: f = C/λ where c is speed of light and λ is the length of the wave f = 3 × 10^8 m/s/ 0.003835 m f = 7.8227 × 10^10 Hz
