Question

How many photons per second are emitted by a 7.50𝑚𝑊 𝐶𝑂2 laser that has a wavelength of 10.6𝜇𝑚?

Answer 1

$P=\dot nh\frac c{\lambda},$

$\dot n=\frac{P\lambda}{hc}=4\cdot 10^{15}~s^{-1}.$