RC charging and discharge
A simple resistor–capacitor circuit has an exponential timescale.
Key knowledge
An ideal series RC circuit driven by constant voltage V₀ from an initially uncharged capacitor has Q(t) = CV₀(1 − e^(−t/RC)). Source-free discharge from Q₀ has Q(t) = Q₀e^(−t/RC).
Values and equations
τ = RC; Q_charge(t) = CV₀(1 − e^(−t/τ)); Q_discharge(t) = Q₀e^(−t/τ)
- τ, t
- Time constant and elapsed time s
- R
- Resistance Ω
- C
- Capacitance F
- V₀
- Constant applied voltage V
- Q, Q₀
- Capacitor charge and initial charge C
Conditions and scope
- R > 0 and C > 0 are constant; t ≥ 0 starts at the specified switch event.
- Ignore leakage, parasitic inductance and nonideal source response.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Section 10.5: charging/discharging equations and time constant.
2026-10-10 · Specified initial-value series RC models only; no universal circuit-response claim.
Entry details
Permanent link to this entry ↗- Record identity
- physics-rc-transient
- Revision
- university-reference.1
- Structured reference record
- University reference