Answer:
Explanation:
First we calculate the energy of the photon
E=(Planck constant × speed of light in vacuum)÷ wave length
E=[tex]\frac{6.626*10^{34}*2.998*10^{8} }{638*10^{-9} } = 3.114*10^{49}[/tex]
Next we find the total energy per second
total energy= [tex]1*10^{-3}W *\frac{1JS^{-1} }{1W} = 1*10^{-3} JS^{-1}[/tex]
Next we calculate the number the photon per second
= total energy ÷ energy of 1 photon
= [tex]\frac{1*10^{-3} JS^{-1} }{3.114*10^{49} } = 3.21*10^{-53} \ photons/sec[/tex]
