RC Time Constant Calculator
Calculate RC time constant (τ=RC) and capacitor charge/discharge times. Essential for filter and timer circuit design.
How It Works
Calculate RC time constant (τ=RC) and capacitor charge/discharge times. Essential for filter and timer circuit design. Enter your values above and click Calculate to get instant results.
Formula
τ = R × C | V(t) = Vs × (1 - e^(-t/τ))
Quick Examples
- R=10kΩ, C=100µF → τ = 1 second
- R=1kΩ, C=10µF → τ = 10ms, 95% charge in ~30ms
Frequently Asked Questions
What is the RC time constant?
The time constant τ=RC is the time for a capacitor to charge to 63.2% of the supply voltage through a resistor. After 5τ, the capacitor is considered fully charged (99.3%).
How does RC affect filter cutoff frequency?
A simple RC low-pass filter has cutoff frequency fc = 1/(2πRC). Frequencies above fc are attenuated by 20dB per decade.