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Grade 12General Physics

why does a capicitor blocks DC and allows AC?

Profile image of Ashwin K John
11 Years agoGrade 12
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1 Answer

Profile image of Harsh Patodia
11 Years ago
Hi Student,

A Capacitor can store the charge as it has two electrodes with dielectric media in between. It does not allow any current to pass through it.
A capacitor stores energy as a function of voltage and resist changes in voltage by drawing current from or supplying current to the source of the voltage change, in opposition to the change.
If a constant voltage (DC) is applied across the capacitor it charges up to some value decided by the voltage and the capacitance. Q=CV
If the voltage is always changing over time (AC) the capacitor attempts to keep it constant. I=C.dV/dt. thus the current appears in the circuit.