Energy stored in a capacitor: Let us consider initially the plates of a capacitor are uncharged and small positive charges are repeatedly transferred from one plate to the other plate. Let at any instant q be the total quantity of charge transferred and v be the potential difference between the plates. Then, q = Cv […]
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Capacitance of a spherical capacitor (outer sphere is earthed): Let us consider A and B are the two concentric spherical shells of radii a and b respectively (b >a). Shell A is charged by Q and the outer surface of shell B is earthed. So –Q charge is induced in the inner surface of B.
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Capacitance: If the charge of a conductor is increased then the potential of the conductor is also increased. Thus, charge (Q)  potential (V) or, Q = CV ——–(1) where C is the capacitance of the conductor and that conductor is called capacitor. From equation (1) C = ——-(2) so, the capacitance of the conductor is
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Dielectrics: Dielectrics are the insulating materials that have no free charge carriers but when electric field is applied on it, there are equal and opposite induced charges produces in the opposite faces of the material. There are two types of dielectric substances. (i) Polar: Polar molecules are those molecules whose centre of gravity of positive
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Electric potential at a point due to electric dipole: Let us consider an electric dipole consists of -q and +q at points A and B respectively separated by a distance 2a. O is the midpoint of the dipole and the dipole moment is = q2a. P is a point, at a distance r from O,
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Electric potential: The electric potential at a point in the electric field due to a charge is the amount of work done to bring a unit positive charge (test charge) from infinity to that point against the electrostatics force of the electric field of source charge. Units of electrostatic potential: C.G.S. unit: statvolt – If
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Concept of conductor: 1. Electric field at the surface of a conductor: Let us consider an elementary surface ds of a conductor of surface charge density . The surface is enclosed by a cylindrical Gaussian surface which is inside and outside of the conductor. As the electric field is perpendicular to the surface so flux
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Concept on electric field: 1. Field of two oppositely charged sheets: Two infinite plane sheets each of surface charge density σ and –σ are placed parallel to each other at a small distance d. Electric field for sheet 1 and 2 are E1 = E2 = . Feld at point A is + 0
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Electric flux: The electric flux through a surface inside an electric field is the total number of electric lines of force crossing the surface in a direction normal to the surface. If E is the electric field creates angle θ with surface of elementary area dS then electric flux, dɸE = EdScosθ Or, dɸE =
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Electrostatic dipole: Electrostatic dipole consists of a pair of equal and opposite point charges separated by a very small distance. Example: H2O, NH3 etc.  Electrostatic dipole moment of an electric dipole is defined as the product of the magnitude of either charge of the dipole and the dipole length. If +q and –q are the
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