Alexander Fufaev

Formula: Charging Process of a Capacitor (RC Circuit)

Voltage-Time Graph of Resistor - Charging a Capacitor

Voltage at Resistor

Voltage measured between the two ends of the resistor. The voltage at the series resistor decreases exponentially with time during charging.

Source voltage

Constant voltage applied to the RC circuit for charging. This is the voltage at time \(t = 0 \).


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 \( 1 \, \mathrm{V} \).

Electrical Resistance

Resistor connected in series with the capacitor. The resistance, together with the capacitance, has an influence on how fast the capacitor can charge.


At the time \( t = 0\) a voltage \( U_{\text R}(0) = U_0\) was present at the resistor of the RC element. With time, \(U_{\text R}(t)\) decreases exponentially to zero.