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11.Dual Nature of Radiation and matter
medium
The work functions of Caesium $(Cs)$,Potassium $(K)$ and Sodium $(Na)$ are $2.14\,eV,2.30\,eV$ and $2.75\,eV$ respectively. If incident electromagnetic radiation has an incident energy of $2.20\, eV$, which of these photosensitive surfaces may emit photoelectrons?
A
$Na$ only
B
$Cs$ only
C
Both $Na$ and $K$
D
$K$ only
(NEET-2023)
Solution
Energy of incident radiation $=2.80\,eV$
Work function of $Cs \rightarrow 2.14\,eV$
Work function of $K \rightarrow 2.30\,eV$
Work function of $Na \rightarrow 2.75\,eV$
Since the work function of potassium and sodium are more than energy of incident radiation hence photons may be emitted from caesium.
Standard 12
Physics
