Question

A green laser pointer emits light with a wavelength of 542 nm. What is the frequency of this light?

Answer 1

As we know that wavelength and frequency is inversely proportional to each other. Greater the wavelength smaller the frequency and vice versa.
 
Solution:

The relation between wavelength and frequency is as follow,

υ = c / λ

where
            υ = frequency = ?
            c = velocity of light = 3.0 × 10⁸ ms⁻¹
            λ = wavenumber = 542 nm = 542 × 10⁻⁹ m
Putting the given values,
    
            υ = 3.0 × 10⁸ ms⁻¹ / 542 × 10⁻⁹ m
Result:
            υ = 5.53 × 10¹⁴ s⁻¹