A monochromatic source of light operating at 15 kW emits 2.5 × 10^22 photons / s. The region of an electromagnetic spectrum to which the emitted…

A monochromatic source of light operating at $\displaystyle 15$ kW emits $\displaystyle 2.5 \times 10^{22}$ photons $\displaystyle / \mathrm{s}$. The region of an electromagnetic spectrum to which the emitted electromagnetic radiation belongs to $\displaystyle \_\_\_\_$. (Take $\displaystyle h=6.6 \times 10^{-34} \mathrm{~J} . \mathrm{s}$ and $\displaystyle c=3 \times 10^8 \mathrm{~m} / \mathrm{s}$ ).