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AP EAMCET202418 May 2024Morning ShiftPhysicsDual Nature of MatterActual

Energy required to remove an electron from aluminum surface is 4.2 eV . If light of wavelength 2000 Å falls on the surface, the velocity of the fastest electron ejected from the surface will be

Options

  1. A8.4 10^5 ~ms ⁻¹
  2. B7.4 10^5 ~ms ⁻¹
  3. C6.4 10^5 ~ms ⁻¹
  4. D8.4 10^6 ~ms ⁻¹

Correct answer

A. 8.4 10^5 ~ms ⁻¹

Step-by-step solution

_ o =4.2 eV , =2000 Å, v _ =? E = 12400 ( in Å) eV = 12400 2000 =6.2 eV By Einstein's photoelectric equation, k _ = E - ₀=6.2-4.2=2 eV 1 2 mv _ ^2=2 1.6 10⁻¹⁹ v _ =8.4 10^5 ~m / s

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