Question

Light of a certain colour has 2500 waves to the millimetre in air. What is its frequency?

Answer 1

`λ = (1 mm)/2500`

= `(10^-3  m)/(2.5 xx 10^3)`

= `1/2.5 xx 10^-6  m`

Frequency, `ν = c/λ = (3 xx 10^8)/(1/2.5 xx 10^-6)`

= 7.5 × 10¹⁴ Hz