GopalKrishna Advanced Rural Research Foundation

GARRF Virtual Engineering & Electronics Laboratory

KALAM ZERO RESEARCH FUNDING LAB

EXPERIMENT 04 RC CIRCUIT CHARGING & DISCHARGING VIRTUAL LAB

⚡ INTRODUCTION — Experiment 04: RC Charging & Discharging

A resistor-capacitor (RC) circuit is one of the simplest circuits in which electrical behaviour changes with time. It is fundamental to timing circuits, filters, sensors, signal processing and electronics.

🎯 Experiment Objective

To study the charging and discharging behaviour of a capacitor through a resistor and determine the circuit time constant.

👨‍🎓 Student Challenge

Do not simply watch the graph. Before running the experiment, predict:

  • Will the capacitor voltage rise linearly or exponentially?
  • What happens to charging current with time?
  • What happens if resistance is increased?
  • What happens if capacitance is increased?

📚 SECTION 1 — Theory

RC Time Constant

The time constant of an RC circuit is:

τ = RC

where:

Charging Equation

When a capacitor is charged from a DC source:

# VC(t) VS (1 − e−t/RC)

The charging current is:

# I(t) (VS/R) e−t/RC

Discharging Equation

When the source is removed and the capacitor discharges:

# VC(t) V0 e−t/RC

Important Observation

At approximately: t = τ the capacitor reaches about: 63.2% of its final charging voltage. During discharge, the voltage falls to about: 36.8% of its initial value.

📈 SECTION 4 — Capacitor Voltage vs Time

The curve is generated directly from the RC equations. During charging the voltage approaches the supply voltage; during discharging it approaches zero.

🧩 SECTION 2 — Capacitor & RC Configuration

Chamundi Live Instruction: Set your values first. When you press START, the teacher will take you to the live experiment and explain what is changing. For easier viewing, zoom out slightly if required.
CHAMUNDI • LIVE GUIDANCE ACTIVE
🟢 Ready. Set the values and start the experiment.

📊 Live Measurements

Time 0.00 s
Capacitor Voltage 0.00 V
Current 0.00 mA
Time Constant 0.100 s
Final Voltage 12.00 V

🔌 SECTION 3 — Live RC Experiment

⏱ SECTION 5 — Time Constant Analysis

Run the experiment to analyse the time constant.

📝 SECTION 6 — Student Observation Record

Run the experiment, pause at selected times and record the capacitor voltage.

Trial Mode R C τ Time VC Current

🔬 SECTION 7 — Engineering Analysis

Start the experiment to generate the analysis.

🎓 SECTION 8 — Experiment Conclusion

Complete the experiment to generate the conclusion.

❓ SECTION 9 — Student Quiz

Q1. The time constant of an RC circuit is:
Q2. After one time constant during charging, the capacitor voltage is approximately:
Q3. Increasing R while keeping C constant will:
Q4. During capacitor charging, the current:

🤖 CHITTI

GARRF Robotics & Engineering AI Mentor

Need help understanding the RC circuit? CHITTI can guide you through the experiment.

💡 Try asking:

"Why does capacitor voltage rise exponentially?"

"What does the RC time constant mean physically?"

"What happens if I double the resistance?"

"Why does charging current decrease?"

👨‍🎓 How to Perform Experiment 04

  1. Select Charging.
  2. Set the supply voltage.
  3. Choose R and C.
  4. Calculate the expected time constant: τ = RC.
  5. Press START.
  6. Observe the capacitor voltage curve.
  7. Observe the charging current.
  8. Pause the experiment at different times.
  9. Record your observations.
  10. Repeat the experiment with different R and C values.
  11. Select Discharging and repeat.
  12. Complete the quiz.
⭐ Engineering Thinking Challenge

Can you predict the capacitor voltage at t = τ, t = 2τ and t = 5τ before looking at the graph?

👩🏽‍🏫
CHAMUNDI AI TEACHER • Experiment 04
CURRENT VIEW Section 1 — Experiment
I am ready to teach you Experiment 04 — RC Charging & Discharging. Press Start Lesson when you are ready.
Ready • Step 0 of 10
Language
Female Indian voice preferred • Browser voice availability may vary