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NEET2019PhysicsDual Nature of MatterActual

The work function of a photosensitive material is 4.0 eV . This longest wavelength of light that can cause photon emission from the substance is (approximately)

Options

  1. A3100 ~nm
  2. B966 ~nm
  3. C31 ~nm
  4. D310 ~nm

Correct answer

D. 310 ~nm

Step-by-step solution

The work function of material is given by aligned & = hv & = hc aligned ..(i) [ v= c ] where, h = Planck's constant =6.63 10⁻³⁴ ~J - s c = speed of length =3 10^8 ~ms ⁻¹ and = wavelength of light Here, =4 eV =4 1.6 10⁻¹⁹ ~J Substituting the given values in Eq. (i), we get 4 1.6 10⁻¹⁹= 6.63 10⁻³⁴ 3 10^8 or = 6.63 10⁻³⁴ 3 10^8 4 1.6 10⁻¹⁹ =3.108 10⁻⁷ ~m 310 ~nm

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