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JEE Main202430 Jan 2024Morning ShiftPhysicsDual Nature of MatterActual

The work function of a substance is 3 . 0 eV . The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately:

Options

  1. A215 nm
  2. B414 nm
  3. C400 nm
  4. D200 nm

Correct answer

B. 414 nm

Step-by-step solution

For longest wavelength, the emitted electron will have nearly zero kinetic energy. Therefore, λ = h c W e ⇒ λ = 1240 nm - eV 3 eV ⇒ λ = 413 . 33 nm ⇒ λ max ≈ 414 nm

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