RC Circuit Simulator
Classroom worksheet · Interactive simulation: https://lkforge.com/tools/physics/rc-circuit/
Name: Date:
Learning objectives
- Describe charging and discharging of a capacitor through a resistor.
- Relate the time constant to resistance and capacitance.
- Interpret the exponential voltage curve.
Variables to change
- Resistance
- Capacitance
- Supply voltage
Procedure
- Charge the capacitor and watch the voltage rise over time.
- Increase the resistance and observe how the charging speed changes.
- Increase the capacitance and repeat.
- Let the capacitor discharge and watch the voltage fall.
Observations
Record how long charging takes as you vary R and C, and sketch the voltage-versus-time curve.
Questions
- Write the time constant of an RC circuit.
- What fraction of full charge is reached after one time constant?
- How does increasing resistance affect charging time?
- Is the charging curve linear?
- After discharging for one time constant, how much voltage remains?
Answer key (instructors)
- 1. τ = R·C.
- 2. About 63% (1 − 1/e) when charging.
- 3. It slows charging — a larger τ means the capacitor charges more slowly.
- 4. No — voltage rises exponentially, fast at first then leveling off toward the supply voltage.
- 5. About 37% (1/e) of the initial voltage.
A capacitor charges and discharges exponentially through a resistor with time constant τ = RC. After one τ it reaches ~63% of full charge (or falls to ~37% when discharging). Larger R or C slows the process.