## 1) Theoretical approach

**In the case of AC voltage**

- When AC voltage is connected with a capacitor, one plate of the capacitor gets charged positively and the other gets negatively charged.
- Later when the direction of AC current changes, the capacitor will change its direction, and thus will get discharged.
- This process continues in the case of AC voltage.

**In the case of DC voltage**

- When DC voltage is connected with the capacitor, one plate of the capacitor gets charged positively and the other gets negatively charged.
- When one plate is completely positive charged and the other is negatively charged, the process stops. The capacitor is saturated and the current flow stops.
- Further, if DC voltage is increased, the capacitor will get damaged.

## 2) Mathematical approach

The reactance of the capacitor is given by the formula, X_{C} = 1/2πfC. Where X_{C} is the reactance, f is the frequency and C is the capacitance value.

**The reactance of capacitor during DC**

Since f = 0 in the case of a DC supply. X_{C} = 1/0 = infinity. The reactance is infinite hence no current passes through the circuit. That’s how a capacitor blocks DC.