Time constant

Symbol: t_c
Unit: (s)

In an electrical circuit consisting of a capacitor of capacitance C and a resistor of resistance R, we can define a time constant t_c for the circuit:

  t_c = RC

When a capacitor charges up, the charge of the capacitor increases exponentially with time.

t_c is the time for the charge to increase to 63% of its final charge.

When a capacitor discharges its charge, the charge of the capacitor decreases exponentially with time.

t_c is the time for the charge to decrease to 37% of its initial charge.