A light emitting diode (LED) is fabricated using GaAs semiconducting material whose band gap is 1.42 eV. The wavelength of light emitted from the LED is: (a) 1243 nm (b) 875 nm (c) 650 nm (d) 1400 nm

Answer: (b). λ = hc/Eg, with hc ≈ 1240 eV nm. λ = (1240)/(1.42) nm ≈ 873 nm So the answer is (b) 875 nm.

A light emitting diode (LED) is fabricated using GaAs semiconducting… | JEE Main 2024 (9 Apr, Shift 1)

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Special Purpose Diodes

A light emitting diode (LED) is fabricated using GaAs semiconducting material whose band gap is $1.42\text{ eV}$ . The wavelength of light emitted from the LED is:

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Answer: (b)

$\lambda = \dfrac{hc}{E_g}$ , with $hc \approx 1240$ eV nm.
$\lambda = \dfrac{1240}{1.42}\ \text{nm} \approx 873\ \text{nm}$
So the answer is (b) $875$ nm.

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