The work function `(phi)` of some metals is listed below. The number of metals which will show photoelectric effect when light of 300 nm wavelength falls on the metals is :

Options

A. 2
B. 4
C. 6
D. 8

Answer

B

Explanation

Energy of photon `= (hc)/lambda J = (hc)/(e lambda)eV`
`=(6.625xx10^(-34)xx3xx10^8)/(300xx10^(-9)xx1.602xx10^(-19))=4.14 eV`
For photoelectric effect to occur, energy of incident photons must be greater than work functions of metal. Hence only Li Na K ad Mg have work functions less than 4.14 eV`.