Capacitor charges with time constant τ=RC, reaching 63% in one τ.
Charging: v_C=V(1-e^{-t/RC}); discharging: v_C=V₀e^{-t/RC}. After 5τ the capacitor is >99% charged. Current i=(V/R)e^{-t/RC}. Timing circuits, debouncing and filters rely on this.
R=10 kΩ and C=100 µF give τ=1 s.
The RC time constant sets how fast a sensor, timer or filter responds, so it controls speed and noise in many systems.
Capacitor charges with time constant τ=RC, reaching 63% in one τ.
The RC time constant sets how fast a sensor, timer or filter responds, so it controls speed and noise in many systems.
It is the time needed to reach 63 percent of the final value during charging, or to fall to 37 percent during discharge.
Five time constants reach about 99 percent, which is a practical rule for settling time.
Typical applications include setting the reset delay of a microcontroller with an RC network, estimating how long a capacitor takes to charge to 99 percent and choosing the time constant for a low-pass filter on a sensor signal.
Study "Dependent sources" first (topic 33 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
τ=RC. 63% at τ. Initial current V/R.
R=10 kΩ and C=100 µF give τ=1 s.
The next topic is "RL circuit transient", which builds directly on this one.
It is classed as Beginner in Electrical Engineering (topic 34 of 106). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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