Modern Physics - JEE Main Question Q.1 A beam of electromagnetic radiation of intensity $6.4 \times 10^{-5} \, \text{W/cm}^2$ is comprised of wavelength, $\lambda = 310 \, \text{nm}$ . It falls normally on a metal (work function $\phi = 2 \, \text{eV}$ ) of surface area of $1 \, \text{cm}^2$ . If one in $10^3$ photons ejects an electron, total number of electrons ejected in 1 second is $10^x$. (hc = $1240 \, \text{eV nm}$, $1 \, \text{eV} = 1.6 \times 10^{-19} \, \text{J}$), then $x$ is _______. Show Answer Solution: Given data: Intensity, $I = 6.4 \times 10^{-5} \, \text{W/cm}^2 = 6.4 \times 10^{-3} \, \text{W/m}^2$ Wavelength, $\lambda = 310 \, \text{nm} = 310 \times 10^{-9} \, \text{m}$ Work function, $\phi = 2 \, \text{eV}$ Area, $A = 1 \, \text{cm}^2 = 10^{-4} \, \text{m}^2$ Planck's constant × speed of light, $hc = 1240 \, \text{eV nm} = 1240 \...