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Question: Answered & Verified by Expert
If K1 and K2 are the maximum kinetic energies of photo electrons emitted when lights of wavelength λ1 and λ2 respectively are incident on a metallic surface and λ1=3λ2. Then
PhysicsDual Nature of MatterNEET
Options:
  • A K1>K2/3
  • B K1<K2 /3
  • C K1=3K2
  • D K2=3K1
Solution:
1532 Upvotes Verified Answer
The correct answer is: K1<K2 /3
Maximum kinetic energies of photo electrons for light of wavelength K1=hcλ1-f ,

Maximum kinetic energies of photo electrons for light of wavelength K2=hcλ2-f

Also given, λ1=3λ2

K2K1=3hcλ1-ϕhcλ1-ϕ=3hcλ1-ϕ3hcλ1-ϕ

Therefore K2K1>3

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