Physics - Modern Physics Question with Solution | TestHub

According to laws of photoelectric effect ${\mathrm{KE}}_{\max }=E-\varphi$ where $\varphi$ is work function and ${\mathrm{KE}}_{\max }$ is maximum kinetic energy of photoelectron. $\begin{array}{l}\therefore hv=e{V}_0+\varphi \\ \text{or }hv=5\mathrm{eV}+6.2\mathrm{eV}=11.2\mathrm{eV}\\ \therefore \lambda =\left(\frac{12400}{11.2}\right)\mathring{A}\approx 1000\mathring{A}\end{array}$ Hence, the radiation lies in ultraviolet region.