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| Formulae and Facts |
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| 1) Electric potential 'V' due to a point charge |
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| 'V' due to dipole (axial line) |
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| 'V' due to dipole (equatorial line) is zero. |
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| 2) P.d and electric field |
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| 3) Capacitance |
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| where Q is charge on either plates and V the p.d between plates. |
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| 4) C for a parallel plate capacitor |
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| where A is area of plates and d the distance between the plates. |
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| 5) Capacitance of a parallel plate on introducing a conducting slab of thickness 't' |
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| 6) Capacitance of a parallel plate on introducing a dielectric slab (er) of thickness t. |
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| 7) Effective capacitance when connected in series |
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| 8) Effective capacitance when connected in parallel |
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| Ceff = C1 + C2 + C3 |
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| 9) Energy stored in capacitor on charging is |
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| 10) SI unit of potential is joule. |
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| SI unit of capacitance is farad. |
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| SI unit of polarisation is Cm-2. |
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| of atomic polarisability 'a' is m3. |
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| SI unit of energy density is Jm-3. |
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| 12) Potential energy of a single charge due to an external field is given by q v(r) where q is charge and v(r) is external potential at point 'r'. |
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| 13) Potential energy of a system of two charges (q1, q2) located at r1, r2 respectively is given by |
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| 14) Potential energy due to dipole moment in a uniform field is |
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| V = -p.E |
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| where p is dipole moment and 'E' the electric field. |
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| 15) The capacitance of a parallel plate capacitor in vacuum is given by |
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| where 'd'
is separation distance of the plates. |
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