# Formula: Charging Capacitor

## Capacitor current

Unit
Capacitor current is the electric current that flows into the plate of the capacitor and thus builds up a voltage on the capacitor. This capacitor current decreases exponentially with time during the charging process, while the capacitor voltage $$U(t)$$ increases exponentially.

## Charging current

Unit
Charging current is the initial current that flows into the capacitor plate at time $$t = 0$$. Its value is given by the applied source voltage.

## Capacitance

Unit
Electrical capacitance is a characteristic quantity of the capacitor and tells how many charges must be brought onto the capacitor to charge the capacitor to the voltage $$1 \, \text{V}$$.

## Electrical Resistance

Unit
Resistor with resistance $$R$$ connected in series with the capacitor. The resistor has an influence on how fast the capacitor can charge.

## Time

Unit
After the source voltage $$U_0$$ is applied (switch is closed), the capacitor starts to charge. The charging current starts to flow through the circuit and decays over time $$t$$.