# Capacitor Charge & Time Constant Calculator

Capacitor Charge & Time Constant Calculator calculates the capacitor charge time and energy for a given supply voltage and the series resistance. The series resistance controls the capacitor charging current. The charging time depends on the value of the capacitance(C) and the series resistance(R). Let us first understand the charging mechanism of a capacitor.

In the above diagram, the resistor(R) has a series connection with a capacitor(C). On switching on the switch(S), the circuit gets complete and current flows through the resistor and capacitor. The capacitor starts charging, and thus the voltage across the capacitor starts building up. The rate at which voltage builds up across the capacitor depends on the time constant of the capacitor.

## RC Time Constant(T)

The RC time constant(T) of the capacitor is the time that the capacitor takes to charge or discharge up to a certain voltage of its maximum voltage.

The capacitor charges up to 63% of its maximum voltage in one time constant, and the depletion time of the capacitor is 37%. The RC time constant of the capacitor depends on the value of the resistor(R) and Capacitor (C). The formula for the RC time constant is;

For example, if the resistance value is 100 Ohms and the capacitance value is 2 Farad, then the time constant of the capacitor will be 100 X 2 = 200 Seconds.

## Energy Stored in a Capacitor

The stored charge in the capacitor is the energy stored by the capacitor. The energy stored in the capacitor depends on the value of the capacitance and the applied voltage. on closing switch(S), the capacitor draws the charging current and builds voltage across it up to the supply voltage.

The formula of the stored energy in the capacitor is;

The energy stored in a 5 Farad capacitance when the applied voltage is 10 volts will be;