Capacitor Charge and Time Constant Calculation, Formula, Example

Capacitor Charge and Time Constant Calculator

All the circuits have some time delay in the input and output in DC or AC current or voltage passes through it. This delay is called the time delay or time constant. The unit of the time constant is T.


In above figure shows how the capacitor gets charged. The resistor R and capacitor C is connected in series and voltage and battery supply DC is connected through the switch S. when switch S closed the voltage is supplied and capacitor gets charged until it gets supply voltage. The charging time it takes as 63% and depletion time of the capacitor is 37%.

There are many applications available in the electrical section such as flash lamp, surge protector etc.



Energy is equals to product of capacitance and voltage is reciprocal of two


Time constant is equals to product of resistance and capacitance

Learn More:   Transformer Cable Size Calculations Calculator



V= Voltage applied to the capacitor in volts

C= Capacitance in farads

R= Resistance in ohms

τ= Time constant in seconds


Let’s consider capacitance C as 1000 microfarad and voltage V as 10 volts.

Let’s apply formula

E= 1000*102 /2

E= 0.0500 joules

Example 2

Let’s consider capacitance C as 2000 microfarad and reactance R as 10000 ohms.

Let’s apply formula

Τ τ = 2000*10000

Τ  τ = 20 seconds



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