How does a capacitor work as a filter?

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I understand that capacitors will charge until it’s “full” and voltage and current = 0 because no more electrons can go through. In AC circuits, capacitors will charge and discharge according to the ups and downs of the sin graph. But how does this filter noise?

Noise being different frequencies than the sin wave that we want?

In: Physics

5 Answers

Anonymous 0 Comments

A capacitor does not allow DC through because it fills up. The closer a signal is to DC (the lower its frequency), the more difficulty it has passing through a capacitor.

This also means that you can have a shunt capacitor – one that allows AC signals to go straight to ground instead of continuing down the wire. This gets rid of them. Meanwhile DC signals cannot pass and so the AC component can be removed.

Combining both, or adding an inductive filter too, can allow us to select a particular range of frequencies that we want to allow through a wire.

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