How many photons are produced in a laser pulse of 0.320 j at 641 nm?

The relationship between energy of a single photon and its wavelength can be determined using the formula E=hc/lambda where h is Planck's constant, c is the speed of light, and lambda is the wavelength in units of meters.  If we can find the energy of a single wavelength of 565 nm, we can then determine the number of photons that total 0.861 J.

Before we can solve for the energy, we need to convert 565...