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Olympiad workbookNSEPDual Nature of Matter

In an experimental set up to study the photoelectric effect a point source of light of power 3.2 mW is used. The source emits mono energetic photons of energy 5 eV and is located at a distance d =0.8 ~m from centre of a stationary metallic sphere of work function W =3.0 eV . The radius of the sphere is R =8 ~mm . Assume that the sphere is isolated and photo electrons are instantly swept away after emission. Also assu

Options

  1. AThe de Broglie wave length of fastest moving photoelectron is nearly 8.7 ~A ^0
  2. BIt is observed that after some time emission of photoelectrons from the surface of metal sphere is stopped, th
  3. CTime after which photo electric emission stops is nearly 111 s
  4. DThe light source emits 4 10¹⁵ photons per sec

Correct answer

D. The light source emits 4 10¹⁵ photons per sec

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