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NEET2023PhysicsDual Nature of MatterActual

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?

Options

  1. AN a   only
  2. BC s   only
  3. CBoth   N a   and   K  
  4. DK   only

Correct answer

B. C s   only

Step-by-step solution

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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