State the factor, which controls:
(i) Wavelength of light and (ii) intensity of light emitted by an LED.

Solution

(i) Wavelength of photons emitted depends upon the band gap. Thus, energy is a factor controlling the wavelength of light.

(ii) The forward current increases as the intensity of light increases and reaches a maximum value. Further increase in the forward current results in decrease of light intensity.

LEDs are biased such that the light emitting efficiency is maximum.