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प्रश्न
State its any ‘two’ uses of photodiode.
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उत्तर
Uses Of Photodiode:-
i. Photodiode is used in optocouplers which are used to couple isolated circuits.
ii. Photodiodes are widely used to detect optical signals.
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संबंधित प्रश्न
Meeta's father was driving her to school. At the traffic signal, she noticed that each traffic light was made of many tiny lights instead of a single bulb. When Meeta asked this question to her father, he explained the reason for this.
Answer the following questions based on above information:
(i) What were the values displayed by Meeta and her father?
(ii) What answer did Meeta's father give?
(iii) What are the tiny lights in traffic signals called and how do these operate?
Explain with the help of a diagram, how depletion region and potential barrier are formed in a junction diode.
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
With what considerations in view, a photodiode is fabricated? State its working with the help of a suitable diagram.
Even though the current in the forward bias is known to be more than in the reverse bias, yet the photodiode works in reverse bias. What is the reason?
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?
Using the necessary circuit diagrams, show how the V-I characteristics of a p-n junction are obtained in
Reverse biasing
How are these characteristics made use of in rectification?
The width of depletion region of p-n junction diode is _______.
(A) 0.5 nm to 1 nm
(B) 5 nm to 10 nm
(C) 50 nm to 500 nm
(D) 500 nm to 1000 nm
Sunil and his parents were travelling to their village in their car. On the way his mother noticed some grey coloured panels installed on the roof of a low building. She enquired from Sunil what those panels were and Sunil told his mother that those were solar panels.
(a) What were the values displayed by Sunil and his mother? State one value for each.
(b) In what way would the use of solar panels prove to be very useful?
(c) Name the semiconductor device used in solar panels. Briefly explain with the help of a diagram, how this device works
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'.
Why is zener diode fabricated by heavily doping both p- and n-sides of the junction?
How is a photodiode fabricated?
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.
Show the output waveforms (Y) for the following inputs A and B of (i) OR gate (ii) NAND gate ?
How does a light emitting diode (LED) work? Give two advantages of LED’s over the conventional incandescent lamps.
What happens to the width of depletion player of a p-n junction when it is (i) forward biased, (ii) reverse biased?
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?
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 band gap of an LED, if it is required to emit light in the visible range? Draw a circuit diagram and explain its action.
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 ______.
What is a solar cell?
Draw solar cell V-I characteristics.
With reference to Semiconductor Physics,
Name the process that causes depletion region in a p-n junction.
Explain photodiode.
What is the magnitude of the potential barrier across a Ge p-n junction?
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 ______.
A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. lt can detect a signal of wavelength ______.
Which one of the following is not the advantage of LED?
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?
If the resistance R1 is increased (Figure), how will the readings of the ammeter and voltmeter change?
Read the following paragraph and answer the questions.
|
LED is a heavily doped P-N junction which under forward bias emits spontaneous radiation. When it is forward-biased, due to recombination of holes and electrons at the junction, energy is released in the form of photons. In the case of Si and Ge diode, the energy released in recombination lies in the infrared region. LEDs that can emit red, yellow, orange, green and blue light are commercially available. The semiconductor used for fabrication of visible LEDs must at least have a band gap of 1.8 eV. The compound semiconductor Gallium Arsenide – Phosphide is used for making LEDs of different colours.
|
- Why are LEDs made of compound semiconductor and not of elemental semiconductors?
- What should be the order of bandgap of an LED, if it is required to emit light in the visible range?
- A student connects the blue coloured LED as shown in the figure. The LED did not glow when switch S is closed. Explain why?
OR
iii. Draw V-I characteristic of a p-n junction diode in
(i) forward bias and (ii) reverse bias
Why a photo-diode is operated in reverse bias whereas the current in the forward bias is much larger than that in the reverse bias? Explain. Mention its two uses.
How can a photodiode be used to measure light intensity?
What energy conversion takes place in a solar cell?
Identify the special purpose diodes 'A', 'B' and 'C' from the given symbols.
Select the wrong statement in the case of LED.
Consider the following statements A and B and identify the correct answer:
- For a solar-cell the I-V characteristics lies in the (IV) quadrant of the given graph.
- In a reverse biased p-n junction diode, the current measured in (μA), is due to majority charge carriers.
A light emitting diode (LED) is fabricated using GaAs semiconducting material whose band gap is 1.42 eV. The wavelength of light emitted from the LED is ______.
Consider the following statements A and B and identify the correct answer:
- For a solar-cell, the I-V characteristics lies in the IV quadrant of the given graph.
- In a reverse biased pn junction diode, the current measured in (A), is due to majority charge carriers.
