Watch a capacitor charge and discharge through a resistor. The time constant τ = R · C is set by the resistor and the capacitor alone — drag the supply-voltage slider and the whole curve grows taller while the timing never moves.
Time constant τ = R · C
470 ms
4.70 kΩ · 100 µF
Capacitor voltage VC
5.96 V
t = 5.00 τ · supply 6.0 V
99.3 % charged
Current now I = (V0/R) e−t/τ
8.60 µA
peak 1.28 mA at t = 0
Settling time 5τ
2.35 s
Half-time τ · ln 2 = 326 ms. After 5τ the capacitor sits at 99.3 % of the supply.
Resistance R4.70 kΩ
Capacitance C100 µF
Supply voltage V06.0 V
Ideal series RC: one resistor, one capacitor, no leakage. Charging starts from an empty capacitor, discharging from a full one.
Try this: run a charge sweep, then drag the supply voltage. The curve stretches upward but the τ readout and the τ guide line do not budge — timing belongs to R and C only.