Question 2.7: Calculate the wavelength frequency and wave number of a light wave whose period is 2.0 × 10–10 s.

Question 2.7: Calculate the wavelength frequency and wave number of a light wave whose period is 2.0 × 10^–10 s.

Answer 2.7:
Frequency (ν) of light = 1/Period
Frequency (ν) = 1/2.0 × 10^–10 s
= 5 × 10⁹ s^-1
Wavelength (λ) of light = c/ ν
c = velocity of light in vacuum = 3×10⁸ m/s
Substituting the value in
λ = c/ ν = 3 × 10⁸ ms^-1/5 × 10⁹ s^-1
λ = 6 × 10^-2 m
Wave number of light = 1/wavelength
= 1/6 × 10^-2 m = 16.66 m^-1