Question

how many photons are produced in a laser pulse of 0.732 J at 607nm?

Answer 1

Find the energy in a photon of that wavelength.
\[E_{\lambda} = \frac{hc}{\lambda}\]
Then divide the total energy by the amount of energy per photon in order to find the number of photons.
\[photons = \frac{E_{total}}{E_{\lambda}}\]