λ=Ehc=1.9×1.6×10−196.6×10−34×3×108=6.54×10−7
=654nm
Red color
JEE Main 2021 — Physics Modern Physics
LED is constructed from Ga−As−P semiconducting material. The energy gap of this LED is 1.9eV. Calculate the wavelength of light emitted and its colour. h=6.63×10−34J−s and c=3×108ms−1
Held on 26 Feb 2021 · Verified 6 Jul 2026.
654nm and red colour
654nm and orange colour
1046nm and red colour
1046nm and blue colour
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