Energy of each photon

Another parameter present in the expected total count formula is the energy P of each photon.

The energy of each photon is:

$$P_{\lambda}=\frac{h\cdot c}{\lambda}=\frac{6.62620\cdot10^{-3... ...} ~m}=\frac{1.986\cdot10^{-19}}{\lambda(\mu m)}~J\cdot ph^{-1}$$ (2.7)