When a voltage is applied to a circuit
containing capacitance, current flows to accumulate
charge in the capacitance:
Q = �idt
= CV
Alternatively, by differentiation with
respect to time:
dq/dt = i = C dv/dt
Note that the rate of change of voltage has a polarity
which opposes the flow of current.
The capacitance C of a circuit is
equal to the charge divided by the voltage:
C = Q / V = �idt
/ V
Alternatively, the capacitance C
of a circuit is equal to the charging current divided by
the rate of change of voltage: C = i / dv/dt = dq/dt / dv/dt = dq/dv |