Question 168 of 200

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