Question
A monochromatic light source of power 5mW emits 8 × 1015 photons per second. This light ejects photo electrons from a metal surface. The stopping potential for this set up is 2V. Calculate the work function of the metal.
Energy of each photon,
$\text{E}=\frac{\text{p}}{\text{n}}=\frac{5\times10^{-3}}{8\times10^{15}}=6.25\times10^{-19}\text{J}=\frac{6.25\times10^{-19}\text{J}}{1.6\times10^{-19}}\text{eV}$
$\text{E}=3.9\text{eV}$
Work function, W0 = E - V0 = (3.9 - 2)eV = 1.9eVGenerate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.