The kinetic energy of most energetic electrons emitted from a metallic surface is doubled when the wavelength λ of the incident radiation is changed from 400 nm to 310 nm. The work function of the metal is -
Answer & explanation
Correct answer: option 3
$K=\frac{12400}{4000}-\phi=3.1-\phi$
$2K=\frac{12400}{4000}-\phi=4-\phi$
$⇒6.2-2\phi=4-\phi$
$or\, 2.2 eV = \phi$
$∴\phi=2.2eV$