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 metal is :

Answer

4

Explanation

Ejection of electron takes place only when the absorbed energy is greater than work function.
`E_("absorbed")=(hc)/(lamda)=(6.626xx10^(-34)xx3xx10^(8))/(300xx10^(-9))`
`=6.626xx10^(-19)J=(6.626xx10^(-19))/(1.6xx10^(-19))eV=4.14eV`
Thus, electron will be ejected from four metals. i.e., Li,Na,K,Mg.