Q 12-11-010NEETNEET 2023Top questionEasy
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?
Answer: (A) Cs only
Concept. Emission needs photon energy greater than the work function.
Step 1. Compare. $2.20 > 2.14$ (Cs) but $< 2.30$ (K) and $< 2.75$ (Na).
Answer. Cs only (Option A).
Solution by Sreeraj P, M.Sc Physics