Url Time constant The RC time constant denoted by τ (tau), is the time required to charge a capacitor to 63.2% of its maximum voltage or discharge to 36.8% of the maximum voltage. Resistor (Ω) Capacitor (μf) Time Constant τ = ms Capacitor Charging Resistor (Ω) Source Volatge (Vs) Time (t in milli seconds) Current I = mA Instantaneous current at given time value Capacitor (μf) Initial Voltage (At, t=0) Voltage across capacitor Vc = V Instantaneous voltage at given time value Capacitor Discharging Resistor (Ω) Charged Capacitor Voltage (Vs) Voltage at time t=0 Instantaneous Voltage Vc = Capacitor (μf) Time (ms) Current I = mA Instantaneous current at given time value