An RC discharging circuit has a closed loop RC circuit with the resistance R in series with the capacitor C. Since the circuit is closed, the charge deposited on the capacitor will tend to even out, just like water evens out when a filled vessel is connected to an empty vessel with a pipe. This movement of the charge will cause the voltage across the capacitor to drop towards zero. The calculator in this page will help you calculate the voltage across the capacitor at any time t.

We shall follow the following circuit. This is a closed RC series circuit. The voltage across the capacitor changes from V_{i} to V_{f} in time *t*. The equation is: V_{f} = V_{i}e^{-t/RC}. This equation has been derived from the charging equation by putting V_{cc} = 0.

## Calculate t when R, C, V_{f} and V_{i} are known

Use this form to find the time taken by the voltage to reach V_{f}.

R: | kΩ | |

C: | μF | |

V_{i}: | V | |

V_{f}: | V | |

## Calculate V_{f} when R, C, t and V_{i} are known

Use this form to find the value of V_{f} after a time t.

R: | kΩ | |

C: | μF | |

V_{i}: | V | |

t: | milliseconds | |

## Calculate R when V_{f}, C, t and V_{i} are known

Use this form to find the value of R that will take the voltage to V_{f} after a time t.

C: | μF | |

V_{i}: | V | |

V_{f}: | V | |

t: | milliseconds | |

## Calculate C when V_{f}, R, t and V_{i} are known

Use this form to find the value of C that will take the voltage to V_{f} after a time t.

R: | kΩ | |

V_{i}: | V | |

V_{f}: | V | |

t: | milliseconds | |

## Capacitor Charging Calculator?

Click here for capacitor charging circuit calculator: Capacitor Charge and Discharge Online Calculator