An LED is constructed from a pn junction based on a certain semi-conducting material whose energy gap is 1.9 eV. Then the wavelength of the emitted light is

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Accepted Answer

Correct answer: D. (d) The wavelength of the emitted light is = hcE_g where h is the Planck's constant, c is the velocity of light in vacuum and E_g is the energy gap. Here, E_g=1.9 eV=1.9 1.6 10^-19 J h=6.63 10^-34 Js ,c=3 10^8 ms^-1 ∴ = (6.63 10^-34 Js)(3 10^8 ms^-1)(1.9 1.6 10^-19 J) =6.5 10^-7 m

$An LED is constructed from a pn junction based on a certain semi-conducting material whose energy gap is 1.9 eV . Then the wavelength of the emitted light is$

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