Question

A metal surface of work function 3 eV is illuminated by photons of energy 2 eV. The kinetic energy of emitted photo-electrons will be

• A. 1 eV
• B. 2 eV
• C. 3 eV
• D. 0

Answer 1

Answer: (D)

Here, work function ${\omega }_0=3eV$ and photon energy $E_0=2eV$
As, Einstein’s photoelectric equation $E_0=W_0+K{E}_0$
So, $K{E}_0=E_0-W_0$
$\Rightarrow K{E}_0=2-3=-1eV$
Since, kinetic energy is a scalar quantity i.e., $KE>0$, positive.
So, the photoelectron does not ejected and $KE=0$