Does a capacitor block DC current?

A capacitor blocks direct current (DC) due to its inherent properties. When a DC voltage is applied, the capacitor initially allows the current to flow as it charges up to the voltage level of the source. Once it reaches this voltage level, the flow of current ceases as the dielectric material within the capacitor becomes fully polarized. This forms an insulating barrier preventing any further DC current from passing through.

Capacitors function in AC circuits as well, where they allow alternating current to pass through by repeatedly charging and discharging with the changing voltage. However, in the specific case of DC, once charged, the capacitor will not allow current to flow, effectively blocking it.

The other responses do not appropriately reflect the behavior of capacitors. For example, stating that a capacitor doesn't block DC current misrepresents its function. Similarly, suggesting that it only acts at high frequencies or when fully charged does not accurately capture its role in blocking DC. Once charged, a capacitor will stop DC current regardless of frequency. This understanding is essential for working with electrical circuits and components.