Question

What is the wavelength of light (in nm) if `1.21*10^21` photons have a total energy of `483 J`?

Answer 1

`lamda=498nm`

Explanation:

First, we need to know the energy of one photon (assuming they all have the same energy).

`"Energy of one photon"=483/(1.21*10^21)~~3.99*10^(-19)J`

`E=hf=(hc)/lamda`

`3.99*10^-19=((6.63*10^-34)(3*10^8))/lamda`

`lamda=((6.63*10^-34)(3*10^8))/(3.99*10^-19)=4.98*10^-7m=498nm`