A beam of electromagnetic radiation of intensity $6.4\times {10}^{-5}\text{W}/{\text{cm}}^2$ is comprised of wavelength, $\mathrm{}\lambda =310\mathrm{n}\mathrm{m}$ . It falls normally on a metal (work function $\phi =2eV$ ) of surface area of $1\mathrm{}{\mathrm{c}\mathrm{m}}^2$ . If one in ${10}^3$ photons ejects an election, total number of electrons ejected in $1\mathrm{}\mathrm{s}$ is ${10}^x$ . $\left(hc=1240\mathrm{e}\mathrm{V}\mathrm{n}\mathrm{m},1\mathrm{e}\mathrm{V}=1.6\times {10}^{-19}J\right),$ then $x$ is ___________