RC time constant: 100kΩ × 100µF = 10.000 s (fc ≈ 0.0 Hz)
Worked answer for a first-order RC network of 100kΩ and 100µF: time constant, cutoff frequency and settling time.
Time constant τ 10.000 s fc ≈ 0.0 Hz · settles in 50.000 s (5τ)
| Resistor (R) | 100kΩ |
| Capacitor (C) | 100µF |
| Time constant τ = R · C | 10.000 s |
| Cutoff frequency fc = 1 / (2π·R·C) | 0.0 Hz |
| Settling time (5τ, ≈99.3%) | 50.000 s |
| Elapsed time | Multiple of τ | Charge |
|---|---|---|
| 10.000 s | 1τ | 63.2% |
| 20.000 s | 2τ | 86.5% |
| 30.000 s | 3τ | 95% |
| 40.000 s | 4τ | 98.2% |
| 50.000 s | 5τ | 99.3% |
A charging capacitor reaches 63.2% of the final voltage after one time constant (10.000 s) and is considered fully charged (≈99.3%) after five — here 50.000 s.
Different values? Enter any R and C in the interactive tool:
Open the RC Time Constant Calculator →Disclaimer: These figures assume an ideal first-order RC network. Real resistors and capacitors carry tolerances, and capacitors have ESR and voltage/temperature dependence, so the measured time constant will differ. Confirm against your parts' datasheets.