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NEET2026PhysicsDual Nature of MatterActual

For a metal of work function 6.6 eV, which of the following wavelengths of incident radiation does not give rise to the photoelectric effect ? (Take Planck's constant as 6.6 10⁻³⁴ J s)

Options

  1. A100 nm
  2. B150 nm
  3. C200 nm
  4. D50 nm

Correct answer

C. 200 nm

Step-by-step solution

The threshold wavelength ₀ is given by ₀ = hc . Substituting the given values: ₀ = 6.6 10⁻³⁴ 3 10^8 6.6 1.6 10⁻¹⁹ ₀ = 3 1.6 10⁻⁷ m ₀ = 1.875 10⁻⁷ m = 187.5 nm For the photoelectric effect to take place, the wavelength of incident radiation must be less than or equal to the threshold wavelength ( ₀ ). Among the given options, 200 nm is greater than 187.5 nm. Thus, radiation of wavelength 200 nm will not give rise to the photoelectric effect. Answer: 200 nm

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