Question

A monochromatic beam of light has a frequency of `6.5 times 10^14` hertz. What color is the light?

Answer 1

Blue.

Explanation:

First we have to calculate the wavelength of the light.
`v= flambda`
`v`= velocity of light
`f`= frequency of light
`lambda`= wavelength of light

`v= flambda`
`lambda= v/"f"`
`lambda`= `(3xx10^8)/"(6.5x10^14)"`
`lambda`= `4.6xx10^-7m` or `460 nm`

Visible light lies between approx. 400 and 700 nm.
`460 nm` is seen as the colour blue in the visible light spectrum.