Connect a charged capacitor across a resistor and it discharges, with charge, voltage and current all decaying exponentially: x = x₀ e⁻ᵗּᵣᶜ. The time constant τ = RC sets the pace. After one time constant the charge has dropped to about 37% of its starting value. Adjust R and C and watch the curve change.
MissionPredict the charge remaining after one time constant.Streak 0Best 0
After one time constant τ = RC, the charge on the capacitor has fallen to about:
time constant τ = RC2.0 s
fraction remaining100%
The blue curve is the charge (or voltage) decaying exponentially. The dashed line marks one time constant, where the value has fallen to 1/e, about 37%, of the start.