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MHT CET202527 Apr 2025Evening ShiftPhysicsDual Nature of MatterActual

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 2.41 eV , which of these photosensitive surfaces may emit photoelectrons?

Options

  1. ANa only
  2. BK only
  3. CBoth K and Cs
  4. DBoth Cs and Na

Correct answer

A. Na only

Step-by-step solution

Photoelectron emission occurs when incident radiation energy E exceeds or equals the work function of the metal. Comparing the given E = 2.41 , eV with each work function: For Caesium: _ Cs = 2.14 , eV , so 2.41 2.14 . For Potassium: _ K = 2.30 , eV , so 2.41 2.30 . For Sodium: _ Na = 2.75 , eV , so 2.41 Emission occurs for Caesium and Potassium, but not Sodium.

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