The work functions of Caesium ( C s ) , Potassium ( K ) and Sodium ( N a ) 2 . 14 eV , 2 . 30 eV and 2 . 75 eV are respectively. If incident electromagnetic radiation has an incident energy of 2 . 20

Question

The work functions of Caesium ( C s ) , Potassium ( K ) and Sodium ( N a ) 2 . 14 eV , 2 . 30 eV and 2 . 75 eV are respectively. If incident electromagnetic radiation has an incident energy of 2 . 20 eV , which of these photosensitive surfaces may emit photoelectrons?NEET 2023 (All India)

TestHub · Accepted Answer

For emission of photoelectrons, incident photon energy should be more than the work function of the metal.
Given:
$h ν = 2.20 eV$ .
Clearly,
$h ν > ϕ_{C s}$ but $h ν < ϕ_{K}$ and $h ν < ϕ_{N a}$ .
Therefore, only $C s$ will emit photoelectrons.

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