Question

What is capacitor AC or DC?

Answer 1

A capacitor can work with both AC (Alternating Current) and DC (Direct Current), but how it behaves in each scenario is different.

### In DC (Direct Current):
- When a DC voltage is applied to a capacitor, the capacitor will charge up to the voltage level of the source.
- After the capacitor is fully charged, no more current flows through it, because a capacitor blocks DC once it's charged.
- So, in the DC case, it acts like an open circuit after charging, and no current flows through it.

### In AC (Alternating Current):
- With AC, the voltage alternates, changing polarity continuously.
- This means the capacitor charges and discharges as the AC voltage changes direction.
- The capacitor continuously allows current to flow (but it's not a direct path like a wire). It "blocks" DC but allows AC to pass through, depending on the frequency of the AC signal.
  
### Key Difference:
- **In DC**, a capacitor acts as a barrier after it's charged (no current flow after full charge).
- **In AC**, the capacitor allows current to flow but with phase shifting between voltage and current.

Capacitors are commonly used in AC circuits, for example, in filtering applications to smooth out voltage fluctuations.