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Explain why the reactance offered by a capacitor decreases with increasing frequency of an alternating voltage |
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Answer» SOLUTION :We KNOW that a capacitor does not allow flow of direct current through it because the gap between the two plates of capacitor offers an infinite resistance. When an alternating voltage is applied across a capacitor, the capacitor plates are alternately charged and DISCHARGED. As a result of this changing charge (and hence potential) a current is established through the capacitor. It is therefore clear that a capacitor will pass more current through it if the charge (or voltage) is changing at a faster RATE i.e., the frequency of alternating voltage supply is higher. It means that the reactance offered by a capacitor decreases with increase in frequency of alternating supply. In fact reactance of a capacitor is GIVEN by: `X_( C) = 1/(C omega) = 2piv C`. |
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