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JEE Main2014PhysicsDual Nature of MatterActual

For LED's to emit light in visible region of electromagnetic light, it should have energy band gap in the range of:

Options

  1. A0.1 eV to 0.4 eV
  2. B0.5 eV to 0.8 eV
  3. C0.9 eV to 1.6 eV
  4. D1.7 eV to 3.0 eV

Correct answer

D. 1.7 eV to 3.0 eV

Step-by-step solution

Energy band gap range is given by, E _ g = hc For visible region aligned & = (4 10⁻⁷ 7 10⁻⁷ ) m & E _ g = 6.6 10⁻³⁴ 3 10^8 7 10⁻⁷ &= 19.8 10⁻²⁶ 7 10⁻⁷ &= 2.8 10⁻¹⁹ 1.6 10⁻¹⁹ & E _ g =1.75 eV aligned

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