Question

If the energy of incident radiation is increased by $25\%$, the kinetic energy of the photoelectrons emitted increases from 0.6 eV to 0.9 eV. The work function of the metal is:

• A. 1 eV
• B. 1.2 eV
• C. 1.5 eV
• D. 0.6 eV

Answer 1

Answer: (A)

1 eV

Answer 2

$\text{ The photoelectric equation is given by:}$
$K.E. = E_{\text{incident}} - \text{Work function} = h \nu - \phi$
We know the initial kinetic energy was 0.6 eV and increased to 0.9 eV when the incident energy was increased by 25%.
Solving this, the work function $\phi$ is found to be 1 eV.