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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
With the help of a neat circuit diagram, explain the working of a photodiode.
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?
How is a photodiode fabricated?
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?
Explain how a potential barrier is developed in a p-n junction diode.
Write the important considerations which are to be taken into account while fabricating a p-n junction diode to be used as a Light Emitting Diode (LED). What should be the order of the band gap of an LED, if it is required to emit light in the visible range? Draw a circuit diagram and explain its action.
The wavelength and intensity of light emitted by a LED depend upon ______.
What is a solar cell?
Draw solar cell V-I characteristics.
Pressure P varies as P = `alpha/beta "exp" (- (alpha x)/"k"_"BT")`, where x denotes the distance, kB is the Boltzmann's constant, T is the absolute temperature and α and β are constant. The dimension of β is ______.
