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Describe briefly with the help of a necessary circuit diagram, the working principle of a solar cell. |
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Answer» Solution :Asolar cell is basically a p-n JUNCTION which generates emf when solar radiation falls on the p - nJunction. The generation of emf by a solar cell, when light falls on it, is due to following three basic processes: (i) Generation of e-h pairs due to incident light (photon energy E = hv `gt E_(g)` ) close to the junction. (II)Separation of electrons and holes due to electric field of the depletion region. As a result electrons are swept to n-side and holes to p-side of junction. (iii) COLLECTION of electrons reaching the n-side and holes reaching p-side by metal contacts provided at the two sides of solar cel. As a result of these three processes, an emf is developed such that p-side becomes positive andn side negative. The voltage obtained is known as "photovoltage" When an external load is connected, as shown in , a PHOTOCURRENT flows through the load. 
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