The surface of a metal is illuminated with the light of 400 nm. The kinetic energy of the ejected photoelectrons was found to be 1.68 eV. The work function of the metal is (hc = 1240 eV. nm)
Answer & explanation
Correct answer: option 2
$∵\frac{hc}{λ}=\frac{1}{2}mv^2+\phi$
$⇒\phi=\frac{hc}{λ}-\frac{1}{2}mv^2=\frac{1240}{400}-1.68=1.41eV$