Discussion Forum

1)

The work function ($\phi$) of some metals is Listed below. The number of metals which will show a photoelectric effect when the light of 300 nm wavelength falls on the metal is

Answer:

Option B

Explanation:

Energy of photon= $\frac{hc}{\lambda}J=\frac{hc}{e \lambda}eV= \frac{6.625 \times 10^{-34} \times 3 \times 10^{8}}{300 \times 10^{-9} \times 1.602 \times 10^{-19}}=4.14 eV$

For a photoelectric effect to occur, the energy of incident photons must be greater than the work function of the metal. Hence, only Li, Na, K and Mg  have  work functions less than 4.14 V