The wavelength and intensity of light emitted by a LED depend upon (a) forward bias and energy gap of the semi

Question 46 of 64

Q. The wavelength and intensity of light emitted by a LED depend upon

(a) forward bias and energy gap of the semiconductor

(b) energy gap of the semiconductor and reverse bias

(d) forward bias only OR Two photodiodes D1 and D2 are made of semiconductors having band gaps of 2.0 eV and 2.2 eV respectively. The diode which will be able to detect light of wavelength 6200 Å is/are

(a) D1 only

(b) D2 only

(d) none of these

West Bengal WbchseWest Bengal HS (WBCHSE) Board 2022MCQ· 1mImportance★★★★★

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An LED's emission colour (wavelength) is set by the semiconductor's band gap, while its brightness (intensity) is controlled by the forward-bias current.

An LED is a forward-biased p-n junction made of a direct band-gap semiconductor. When forward biased, electrons and holes are injected across the junction and recombine, releasing energy as photons.

Wavelength: the photon energy released on recombination $\approx$ the band gap energy $E_g$ , so $\lambda = hc/E_g$ — set by the material's energy gap. …

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Same / Similar Concept — real previous-year questions on the same or a closely similar concept, not this exact question.

CBSE 2023Set ANNUAL1 mark
$Q. Light emitting diodes emit light in which bias? OR Write the Boolean expression for NOR gate.$
›Reveal solutionSolution

An LED is a forward-biased p-n junction diode; light is emitted only when the junction is forward biased, allowing electron-hole recombination that releases energy as photons.

A light emitting diode (LED) is a heavily doped p-n junction that emits light through spontaneous emission when charge carriers recombine. This recombination only happens efficiently when the diode is forward biased — the p-side connected to the positive terminal and n-side to the negative terminal of the source. Forward bias injects majority carriers (el …

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CBSE 2022Set ANNUAL1 markMCQ
$Q. The wavelength and intensity of light emitted by a LED depend upon$
(a) forward bias and energy gap of the semiconductor
(b) energy gap of the semiconductor and reverse bias
(c) energy gap only
(d) forward bias only OR Two photodiodes D1 and D2 are made of semiconductors having band gaps of 2.0 eV and 2.2 eV respectively. The diode which will be able to detect light of wavelength 6200 Å is/are
(a) D1 only
(b) D2 only
(c) both D1 and D2
(d) none of these
›Reveal solutionSolution
An LED's emission colour (wavelength) is set by the semiconductor's band gap, while its brightness (intensity) is controlled by the forward-bias current.

An LED is a forward-biased p-n junction made of a direct band-gap semiconductor. When forward biased, electrons and holes are injected across the junction and recombine, releasing energy as photons.

Wavelength: the photon energy released on recombination $\approx$ the band gap energy $E_g$ , so $\lambda = hc/E_g$ — set by the material's energy gap. …
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CBSE 2020Set ANNUAL1 markMCQ
$Q. Type of material which emits white light in LED :$
(a) GaInN
(b) SiC
(c) AlGaP
(d) GaAsP
›Reveal solutionSolution
Among the given semiconductor compounds, GaInN (Indium Gallium Nitride) is the material used in white-light-emitting LEDs.

Working

Different LED materials emit different colours depending on their band gap:

GaInN (Gallium Indium Nitride): emits blue/UV light efficiently and, combined with a yellow phosphor coating (or by combining red/green/blue chips), is the standard material used to produce white-light LEDs. …
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Q.The wavelength and intensity of light emitted by a LED depend upon

Concept understanding — Light Emitting Diode (LED)

Q.The wavelength and intensity of light emitted by a LED depend upon

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