When a light of wavelength 150 nm is incident on silver surface a potential of 3.58 V is required to stop the photoelectrons from reaching the collector plate. Find the potential required to stop photoelectrons when a light of wavelength 200 nm is incident on it? (Work function of silver is 4.7 eV)

1.51 V

The correct answer is Option (1) → 1.51 V

According to Einstein Photoelectric equation -

$eV_s=h\frac{c}{λ}-\phi$

$∴\frac{eV_0'+\phi}{eV_0+\phi}=\frac{λ}{λ'}=\frac{100}{200}=\frac{1}{2}$

$2eV_0'+2\phi=eV_0+\phi$

$eV_0'=\frac{eV_0-\phi}{2}=\frac{7.7-4.7}{2}=1.5V$