Spectrum and Wavelength calculations

Question

9. The blue color of the sky results from the scattering of sunlight by air molecules. The blue light has a frequency of about 7.5 x1014 Hz. Calculate the wavelength, in nm, associated with this radiation.

Answer 1

Electromagnetic waves all travel at the speed of light when in vacuum, and essentially this same speed in normal air. Since wave speed is product of frequency and wavelength, c = f λ and λ = c/f = (3.00 x 10⁸ m/s) / (7.5 x 10¹⁴ Hz) = 4.00 x 10^-7 m = 400 x 10^-9 m = 400 nm.