Question

Which of the following is/are correct regarding the working principle of LED?

• A. When an electron makes a transition to the valance band to fill up a hole in a p-n junction, it emits energy in the form of photon
• B. The energy of this photon is equal to the energy gap between conducction band and valance band energy levels
• C. Energy of a photon is the product of frequency of electromagnetic radiation (f) and Planck constant (h).
• D. Both A and B

Answer 1

Answer: (A), (B), (C)

The energy of this photon is equal to the energy gap between conducction band and valance band energy levels
When an electron makes a transition to the valance band to fill up a hole in a p-n junction, it emits energy in the form of photon
Energy of a photon is the product of frequency of electromagnetic radiation (f) and Planck constant (h).

The Light Emitting Diode is connected in reverse bias.
The electrons travel from n-side to p-side crossing the large potential barrier under application of external potential. In this process, electron makes a transition to the valance band to fill up a hole in a p-n junction, and emits energy in the form of photon. The energy of this photon is equal to the energy gap between conduction band and valance band energy levels. This energy of photon is expressed as $E=h\nu$.