When LED is manufactured by using aluminium gallium arsenide (AlGaAs), it emits (a) ultra-violet light (b) infra red radiation (c) green light (d) blue light

Answer: (b). The colour of an LED depends on the band gap of its material. AlGaAs has a band gap of about 1.4 to 1.6 eV, giving λ ≈ 800 to 880 nm. This is beyond the red end, i.e. infrared. So the answer is (b) infra red radiation.

When LED is manufactured by using aluminium gallium arsenide… | MHT CET 2025 (5 May, Shift 2)

Q17MHT CET 2025 · 5 MAY · SHIFT 2Easy

Special Purpose Diodes

When LED is manufactured by using aluminium gallium arsenide (AlGaAs), it emits

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Answer: (b)

The colour of an LED depends on the band gap of its material.
AlGaAs has a band gap of about $1.4$ to $1.6$ eV, giving $\lambda \approx 800$ to $880$ nm.
This is beyond the red end, i.e. infrared.
So the answer is (b) infra red radiation.

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