Question

What is the frequency of a light source that has a wavelength of 807 nm? What is the energy of this wave?

Answer 1

`nu=3.71xx10^(14)s^(-1)`

`E=2.46xx10^(-19)J`

Explanation:

The relationship between the wavelength `lambda` and the frequency `nu` is the following:

`lambda=c/(nu)`

where `c` is the speed of light `c=2.9979xx10^8m/s`.

Therefore, to calculate the frequency of a wave of `807 nm`:

`nu=c/(lambda)=(2.9979xx10^8cancel(m)/s)/(807xx10^(-9)cancel(m))=3.71xx10^(14)s^(-1)`

`nu` could also be reported in units of Hertz: `nu=3.71xx10^(14)Hz`

The energy `E` of this wave can be calculated from:

`E=hnu` where `h=6.626xx10^(-34)J*s` is called Planck's constant.

`E=hnu=6.626xx10^(-34)J*cancel(s)xx3.71xx10^(14)cancel(s^(-1))=2.46xx10^(-19)J`