RC Time Constant Calculator:
Enter the values of resistance, R(Ω) and capacitance, C(F) to determine the value of RC time constant, τ(s).
RC Time Constant Formula:
The RC time constant, denoted as τ, is a fundamental concept in electronics and electrical circuits involving resistors (R) and capacitors (C). It describes the time required for a capacitor to charge or discharge to approximately 63.2% of the difference between its initial and final voltage when subjected to a constant voltage source. This behaviour is crucial in timing circuits, filters, and signal processing applications.
The RC time constant is directly proportional to the resistance R in ohms (Ω) and the capacitance C in farads (F). The larger the resistance or capacitance, the slower the capacitor charges or discharges, resulting in a longer time constant. Conversely, smaller resistance or capacitance values lead to a quicker response and a shorter time constant.
In a charging capacitor, the voltage across the capacitor increases exponentially, approaching the supply voltage asymptotically. During discharge, the voltage decreases exponentially, approaching zero. The RC time constant provides a quantitative measure of these exponential changes.
RC time constant, τ(s) in seconds is calculated by multiplying the resistance, R(Ω) in ohms by the capacitance, C(F) in Farads.
RC time constant, τ(s) = R(Ω) * C(F)
τ(s) = RC time constant in seconds, s.
R(Ω) = resistance in Ohms, Ω.
C(F) = capacitance in Farads, F.
RC Time Constant Calculation:
1.A circuit has a resistor with 1,000Ω and a capacitor with 10μF (microfarads). Find the time constant.
Given: R(Ω) = 1000 Ω, C(F) = 10 * 10-6F.
RC time constant, τ(s) = R(Ω) * C(F)
τ(s) = 1000 * 10 * 10-6
τ(s) = 0.01s.
2.In a circuit, the RC time constant is 5s, and the resistance is 250Ω. Calculate the capacitance.
Given: R(Ω) = 250 Ω, τ(s) = 5s.
RC time constant, τ(s) = R(Ω) * C(F)
C(F) = τ(s) / R(Ω)
C(F) = 5 / 250
C(F) = 0.02F.