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JEE Main 2014 (12 Apr, Shift 1) · Special Purpose Diodes

Special Purpose Diodes question from JEE Main 2014 (12 Apr, Shift 1)

Q89JEE Main 2014 · 12 APR · SHIFT 1Easy

Special Purpose Diodes

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

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Answer: (d)

  1. Visible light spans about 400400 nm to 700700 nm.
  2. E=1240λ (nm)E = \dfrac{1240}{\lambda\,(\text{nm})} eV: 1240700≈1.8\dfrac{1240}{700} \approx 1.8 eV and 1240400=3.1\dfrac{1240}{400} = 3.1 eV.
  3. So the band gap must be about 1.71.7 eV to 3.03.0 eV.
  4. So the answer is (d).
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