Physics - Modern Physics Question with Solution | TestHub

${\lambda }_0=3250\times {10}^{-10}\mathrm{ m}$

$\lambda =2536\times {10}^{-10} \mathrm{ m}$

$\varphi =\frac{hc}{{\lambda }_0}=\frac{1242 eV-\text{n}\text{m}}{325 \text{n}\text{m}}=3.82 \mathrm{eV}$

$h\nu =\frac{hc}{\lambda }=\frac{1242 eV-\text{nm}}{253.6 \text{nm}}=4.89 \mathrm{eV}$

By Einstein’s photoelectric equation

$K_{\mathrm{m}\mathrm{a}\mathrm{x}}=\frac{hc}{\lambda }-$$\frac{hc}{{\lambda }_0}$

$K{E}_{\max }=\left(4.89-3.82\right)\mathrm{ eV}=1.07 \mathrm{eV}$

$\frac{1}{2}m{v}^2=1.07\times 1.6\times {10}^{-19}$

$v= \sqrt{\frac{2\times 1.07\times 1.6\times {10}^{-19}}{9.1\times {10}^{-31}}}$

$v=0.6\times {10}^6\mathrm{ m/s}$