The longest wavelength of light that can initiate photo electric effect in the metal of work function 9 eV is

The longest wavelength of light that can initiate photo electric effect in the metal of work function 9 eV is
  1. $1.37 \times 10^{-7} \mathrm{~m}$
  2. $1.5 \times 10^{-7} \mathrm{~m}$
  3. $3.7 \times 10^{-7} \mathrm{~m}$
  4. $4 \times 10^{-7} \mathrm{~m}$

Solution

for metal, $\phi_0=9 e^v$ $\therefore \phi_{\mathrm{o}}=\frac{\mathrm{h}_{\mathrm{c}}}{\lambda_{\mathrm{o}}} \Rightarrow \lambda_{\mathrm{o}}=\frac{1240 \mathrm{~eV}-\mathrm{nm}}{9 \mathrm{~eV}}=1.37 \times 10^{-7} \mathrm{~m}$

Asked in: AP EAMCET 2024 (19 May Shift 2)

Practice more Dual Nature of Matter and Radiation questions on Aicharya