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प्रश्न
Colour of light emitted by LED depends upon__________________ .
- its forward bias
- its reverse bias
- the band gap of the material of semiconductor
- its size
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उत्तर
the band gap of the material of semiconductor
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संबंधित प्रश्न
With the help of a neat circuit diagram, explain the working of a photodiode.
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?
Carbon, silicon and germanium have four valence electrons each. These are characterised by valence and conduction bands separated by energy band gap respectively equal to (Eg)C, (Eg)Si and (Eg)Ge. Which of the following statements is true?
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
State its any ‘two’ uses of photodiode.
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
Draw the circuit diagram of a full wave rectifier using p-n junction diode.
Explain its working and show the output, input waveforms.
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?
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 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 ______.
Draw solar cell V-I characteristics.
A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. lt can detect a signal of wavelength ______.
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?
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.
Draw the circuit diagram of an illuminated photodiode and its I-V characteristics.
How can a photodiode be used to measure light intensity?
What energy conversion takes place in a solar cell?
