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प्रश्न
Briefly explain its working. Draw its V - I characteristics for two different intensities of illumination ?
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उत्तर
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Current AB that flows when no light is incident is called dark current.
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When photons of light having energy hν fall on the photodiode, more electrons from the valence band move to the conduction band, provided hv is greater than the forbidden energy gap.
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The current in the circuit increases. As the intensity of light is increased, the current goes on increasing (represented by the part BC).
- When the current does not increase with the increase in intensity of light, the photodiode is said to be saturated. The portion CD of the graph represents the saturated current.
V-I characteristics:
संबंधित प्रश्न
If a small voltage is applied to a p-n junction diode, how will the barrier potential be affected when it is (i) forward biased
Write briefly the important processes that occur during the formation of p−n junction. With the help of necessary diagrams, explain the term 'barrier potential'.
Draw V − I characteristics of a p-n junction diode. Answer the following questions, giving reasons:
(i) Why is the current under reverse bias almost independent of the applied potential up to a critical voltage?
(ii) Why does the reverse current show a sudden increase at the critical voltage?
Name any semiconductor device which operates under the reverse bias in the breakdown region.
Draw the circuit diagram of a full wave rectifier using p-n junction diode.
Explain its working and show the output, input waveforms.
The plate resistance of a triode is 8 kΩ and the transconductance is 2.5 millimho. (a) If the plate voltage is increased by 48 V and the grid voltage is kept constant, what will be the increase in the plate current? (b) With plate voltage kept constant at this increased value, by how much should the grid voltage be decreased in order to bring the plate current back to its initial value?
The wavelength and intensity of light emitted by a LED depend upon ______.
Explain photodiode.
The amplifiers X, Y and Z are connected in series. If the voltage gains of X, Y and Z are 10, 20 and 30, respectively and the input signal is 1 mV peak value, then what is the output signal voltage (peak value)
- if dc supply voltage is 10V?
- if dc supply voltage is 5V?
Draw the circuit diagram of an illuminated photodiode and its I-V characteristics.
Select the wrong statement in the case of LED.
