Question

state the factors which control the wavelength of light emitted by an LED​

Answer 1

Answer:

(i) Wavelength of light and (ii) intensity of light emitted by an LED. (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.

Answer 2

The factors which control the wavelength of the light emitted by the LED are:

1. Bandgap of the material of the LED

• LEDs are made of semiconductors and hence have a direct bandgap
• As a result during recombination, the energy released is in the form of photons.
• If it was an indirect bandgap, phonons would have been released.
• The photon released is responsible for the light emission.
• The direct bandgap is the reason for photon release which in turn controls the wavelength of light emitted.

2. Biasing of the LED.

• LEDs are forward-biased p-n junctions diodes.
• In forward-biasing, the depletion region is small and hence the current flow is maximum.
• As a result, the recombination rate of electrons in the depletion region is also maximum.
• This leads to maximum energy release in the form of more photons.
• As the number of photons emitted increases, intensity and hence the wavelength also increases.