Why can a capacitor be used as a noise countermeasure component?

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A. The capacitor has a shielded DC current that is characterized by an alternating current. In an electronic device that operates with a DC voltage, the AC component becomes a noise that affects the stability of the operation. To this end, the AC component is routed to the ground by grounding the capacitor. By supplying only the DC component to the electronic device, unnecessary AC components (noise) are removed to ensure proper operation.
 
Remove unwanted signals (noise) and remove the required signals.