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Define dielectric constant of a medium. Briefly explain why the capacitance of a parallel plate capacitor increases, on introducing a dielectric medium between the plates. |
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Answer» Solution :Dielectric constant (K) of a medium is defined as the ratio of absolute permittivity (`epsi`) of the medium to the permittivity of FREE SPACE (`epsi_0`). Alternately dielectric constant of a medium is defined as the ratio of the capacitance of a parallel plate capacitor when filled with that medium to its capacitance with free space as the dielectric. When a dielectric medium is introduced between the plates of a parallel plate capacitor, the dielectric is polarised by the electric field between the plates. As a RESULT, the electric field and hence potential DIFFERENCE between the plates of capacitor DECREASES. Consequently, the capacitance of the capacitor increases. |
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