In an experiment on the photoelectric effect, monochromatic light of wavelength $\lambda$ is incident on a metal surface of work function $\varphi$. The stopping potential of 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:

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