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Explain, with the help of a circuit diagram, the working of a photo diaode. Write briefly how it is used to detect the optical signals. |
Answer» Solution : Working of photo -diode - A junction diode made from light sensitive semiconductor is called a photo diode. A PHOTODIODE is an electrical device USED to detect and convert light into on 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//lambda`, is SUFFICIENT to break a valence bond. When such light falls on the junction, new hole -electron pairs are created. The numberof charge carriers increases and hence the conductivityof the junction increase . If the junction is connectedto some circuit, the CURRENT in the circuit is controlled by the intensity of the incident light. |
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