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| Energy Stored in a Capacitor |
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| While charging a capacitor, a battery transfers positive charge from negative to the positive plate. So some work is done in transferring this charge, which is stored in the capacitor in the form of electrostatic energy. |
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| This energy can be recovered by discharging the capacitor in a circuit just as one can recover the potential energy stored in a stretched bow by releasing the bow to send an arrow flying. |
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| Suppose the capacitor is charged gradually, then, the work done in giving an additional charge dq is |
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| Other equivalent expressions are: |
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| If capacitance 'C' is measured in Farad, charge q in coulomb, potential difference 'V' in volt, then electrostatic potential energy 'u' is expressed in Joule. Energy stored in a capacitor is reversibly reconvertible into some other form. |
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