# Time Constant Formula

## Time Constant Formula

Any electronic circuit that receives a voltage, either DC or AC, notices some sort of “time-delay” between its input and output. The Time Constant or Time Delay of an Electric Circuit are terms used to describe this delay. The inductive or capacitive reactive components that are connected to an electric circuit will determine the final time constant. When a DC voltage (increasing) is applied to the capacitor while it is being discharged, the capacitor charges up. When the voltage is reduced, the capacitor discharges (in the opposite direction).

These characteristics of a capacitor cause them to function like miniature batteries that can release or store energy as needed. The capacitor plate’s charge is specified as Q = VC. Capacitor charging and discharge do not occur instantly; rather, they take some time. The Time Constant, denoted by Tau (), is the amount of time needed to charge or discharge the capacitor to a particular percentage of its highest supply value.

## Universal Time Constant Formula

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### Follow the following steps to analyse an RC and L/R circuit

Step 1: Determine the time constant of the circuit

Step 2: Identify the quantity to be calculated (the quantity whose change is opposed by the reactive component)

Step 3: Find the starting and final values of that quantity.

Step 4: Substitute all the values determined in the Universal Time Constant formula and then find Change in quantity.

Step 5: If the starting value is zero then the change in quantity is equal to the value calculated using the formula. If not, add the change to the starting value to find the answer.