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प्रश्न
How does a light emitting diode (LED) work? Give two advantages of LED’s over the conventional incandescent lamps.
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उत्तर
When we apply sufficient voltage to LED, electron move across the junction into the p-region and get attracted to the holes there. Thus, electrons and holes recombine. During each recombination, electric potential energy is converted into electromagnetic energy and a photon of light with a characteristic frequency is emitted, this is how LED works.
Advantage of LEDs over incandescent lamps
(1) Since LEDs do not have a filament that can burn out, they last longer.
(2) They do not get hot during use.
संबंधित प्रश्न
Using the necessary circuit diagrams, show how the V-I characteristics of a p-n junction are obtained in
Forward biasing
How are these characteristics made use of in rectification?
The current in the forward bias is known to be more (~mA) than the current in the reverse bias (~μA). What is the reason, then, to operate the photodiode in reverse bias?
Describe briefly, with the help of a diagram, the role of the two important processes involved in the formation of a p-n junction.
What happens to the width of depletion player of a p-n junction when it is (i) forward biased, (ii) reverse biased?
Draw the V-I characteristics of an LED. State two advantages of LED lamps over convertional incandescent lamps.
The wavelength and intensity of light emitted by a LED depend upon ______.
With reference to Semiconductor Physics,
Name the process that causes depletion region in a p-n junction.
What is the magnitude of the potential barrier across a Ge p-n junction?
Consider the following statements (A) and (B) and identify the correct answer.
- A Zener diode is connected in reverse bias when used as a voltage regulator.
- The potential barrier of the p-n junction lies between 0.1 V to 0.3 V.
If the resistance R1 is increased (Figure), how will the readings of the ammeter and voltmeter change?
