Question

How many photons are produced in a laser pulse of 0.655 J at 607 nm?

Answer 1

E= ch/(wavelength)

E= Energy per photon

So,

E= (6.626x10^-34)(3.00x10^8)/(607x10^-9)= 3.27 x10^-19 j

Then,

.655/(3.27x10^-19) = 2.00x10^18 photons

Hope this helps

Might wanna run through it yourself just to double check numbers :)