Question

What is the wavelength (in nm) of the red light emitted by a barcode scanner that has a frequency of `4.62 * 10^14s^-1`?

Answer 1

I found `649nm`

Explanation:

You can convert frequency, `nu`, into wavelength, `lambda`, using the speed of light in vacuum as:
`c=lambda*nu`
rearranging:
`lambda=c/nu=(3xx10^8)/(4.62xx10^14)=6.4935xx10^-7m~~649nm`