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प्रश्न
Explain, with the help of a circuit diagram, the working of a photo-diode. Write briefly how it is used to detect the optical signals.
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उत्तर
Working of photo diode:
A junction diode made from light sensitive semi-conductor is called a photodiode.
A photodiode is an electrical device used to detect and convert light into an energy signal through the use of a photo detector. It is a pn-junction whose function is controlled by the light allowed to fall on it. Suppose, the wavelength is such that the energy of a photon, hc/λ, is sufficient to break a valance bond. When such light falls on the junction, new hole-electron pairs are created. The number of charge carriers increases and hence the conductivity of the junction increases. If the junction is connected in some circuit, the current in the circuit is controlled by the intensity of the incident light.
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संबंधित प्रश्न
Explain briefly with the help of necessary diagrams, the reverse biasing of a p-n junction diode. Also draw characteristic curves.
Explain, with the help of a circuit diagram, the working of n-p-n transistor as a common emitter amplifier.
The drift current in a reverse-biased p-n junction is increased in magnitude if the temperature of the junction is increased. Explain this on the basis of creation of hole-electron pairs.
In a p-n junction with open ends,
(a) there is no systematic motion of charge carries
(b) holes and conduction electrons systematically go from the p-side to n-side and from the n-side to p-side respectively
(c) there is no net charge transfer between the two sides
(d) there is a constant electric field near the junction.
Find the equivalent resistance of the network shown in figure between the points A and B.
(Assume that the resistance of each diode is zero in forward bias and is infinity in reverse bias.)
A diode, a resistor and a 50 Hz AC source are connected in series. The number of current pulses per second through the resistor is __________ .
Choose the correct option.
Current through a reverse-biased p-n junction increases abruptly at:
The depletion layer in the p-n junction diode is caused by ______.
For an ideal diode, in forward and reverse biased condition the resistance is respectively ______.
In p-n junction diode ______.
