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Physics · PYQ NEET UG 2023
हिन्दीThe work functions of Caesium (Cs), Potassium (K) and Sodium (Na) are \( 2.14\text{ eV} \), \( 2.30\text{ eV} \) and \( 2.75\text{ eV} \) respectively. If incident electromagnetic radiation has an incident energy of \( 2.20\text{ eV} \), which of these photosensitive surfaces may emit photoelectrons?
Correct answer · Option 4
Cs only
Explanation
Photoelectric emission occurs only when the incident photon energy (\( 2.20\text{ eV} \)) is greater than the work function of the metal. Since only Caesium has a work function (\( 2.14\text{ eV} \)) less than \( 2.20\text{ eV} \), only Cs will emit photoelectrons.
