RC Circuit (Charging & Discharging)
Charge or discharge a capacitor through a resistor — adjust the source voltage, resistance, and capacitance to see the exponential voltage/current curves and the circuit's time constant.
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What you can adjust
- Mode
- 0 – 1
- Source voltage (V0)
- 1 – 24 V
- Resistance (R)
- 100 – 5000 ohm
- Capacitance (C)
- 0.0001 – 0.002 F
Charging: the capacitor starts empty and fills toward the source voltage. Discharging: it starts full and empties through the resistor.
The DC EMF the capacitor charges toward (or starts at, when discharging) — 9V is a common real battery voltage.
Bigger resistance slows the charge/discharge down (tau = R*C) and lowers the peak current (I = V0/R).
Real capacitors are usually specified in microfarads (uF) — this range is 100uF to 2000uF (0.0001F to 0.002F). Bigger capacitance slows the charge/discharge down (tau = R*C).
About this simulation
What it shows
A capacitor charges or discharges through a resistor, and its voltage and the current are drawn over time as smooth curves.
The key idea
The voltage changes exponentially, with a time constant τ = R × C. After one time constant a charging capacitor has reached about 63% of the source voltage, and the current starts at V₀/R and fades away.
Try this
Raise Capacitance (C) from 0.001 F to 0.002 F: the time constant doubles from 1 s to 2 s, so charging takes twice as long.