Calculate the frequency:
Calculate the frequency and wave number for the EM radiation having a wavelength of 10 m.
Answer:
We know that ν = c/λ and c = 3.0 × 1010 m s-1
Substituting the values, we get
ν =3.0 × 1010 s -1/10m = 3.0 × 109 s -1 = 3.0 × 109 Hz.
Further, as wavenumber and wavelength are related as, 
= 1/λ
Substituting the values of the wavelength we get, wave number
= 1/10 m = 0.1m -1