Physics - Modern Physics Question with Solution | TestHub

Given that,$2\mathrm{ }\mathrm{eV} \le \varphi \le 5\mathrm{ }\mathrm{eV}$

Wavelength corresponding to the minimum and maximum values of work function are

${\lambda }_{max}=\frac{hc}{E}=\frac{4\times {10}^{-15}\times 3\times {10}^8}{2}$

$= 6\times {10}^{-7}\mathrm{m}=600\mathrm{ }\mathrm{nm}$

And${\lambda }_{min}=\frac{hc}{E}=\frac{4\times {10}^{-15}\times 3\times {10}^8}{5}$

$= 2.4\times {10}^{-7}\mathrm{m}=240\mathrm{ }\mathrm{nm}$

Clearly wavelength range would be$240\le \lambda \le 600$

Thus, the wavelength 650 nm is not suitable for the photoelectric effect.