The energy of light of wavelength λ is given by E=hv=λhc⇒λ=Ehc Here, h= Planck's constant =6.63×10−34 J−s c= speed of light =3×108 m/s E= energy gap =1.9eV=1.9×1.6×10−19 J Substituting the given values in Eq. (i), we get ⇒λ=1.9×1.6×10−196.63×10−34×3×108=6.54×10−7 m≈654 nm Thus, the wavelength of light emitted from LED will be 654 nm.
An LED is constructed from a p-n junction diode using GaAsP. The energy gap is 1.9 eV. The wavelength of the light emitted will be equal to
NEET UG 2019 — Physics Modern Physics
2019mcqmedium
An LED is constructed from a p-n junction diode using GaAsP. The energy gap is 1.9eV. The wavelength of the light emitted will be equal to
Official previous-year question
Held on 30 Apr 2019 · Verified 9 Jul 2026.
Options
- A
10.4×10−26 m
- B
654 nm
- C
654A˚
- D
654×10−11 m
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