The energy required to remove and elrctron from the surface fo sodium metal is ` 2. 3 eV`. What is the longest wavelength of radiation with which it can shown photoelectric effect ?

Explanation

Energy required to shown photo emission
` = 2 . 3 eV = 2.3 xx 1.6 xx 10^(-19 J`
Thus ` E= ( hC)/(lambda) "or" lambda = (hc)/E`
` =( 6.626 xx 10^(-34) xx 3xx 10^(8))/( 2.3 xx 1.6 xx 10^(-19)) = 5. 4 xx 10^(-7)m`
Thus longest wavelength to shown photoelectric effect
` = 5. 4 xx 10 ^(-7) m`.