In a photoelectric effect experiment, monochromatic radiation of wavelength $\lambda$ is incident on a metal target with work function $\varphi$. The stopping potential for the emitted photoelectrons is measured to be $V_s$.

If $h$ is the Planck constant, $c$ is the speed of light in a vacuum, and $e$ is the elementary charge, what physical quantity is represented by the expression:

$$\frac{hc}{e{V}_s+\varphi }$$