GARRF Virtual Lab — Experiment 03

⚡ Experiment 03 — Kirchhoff's Laws

In this experiment you will investigate two fundamental laws used to analyse electrical circuits: Kirchhoff's Current Law (KCL) and Kirchhoff's Voltage Law (KVL).

🎯 Experiment Objective

To verify experimentally that the algebraic sum of currents at a junction is zero and that the algebraic sum of voltages around a closed loop is zero.

👨‍🎓 Student Challenge

Before pressing RUN EXPERIMENT, predict:

Which branch will carry the larger current?
What should happen to the current at the junction?
Will the sum of voltage rises and drops around a loop be zero?

Section 1. Theory

Kirchhoff's Current Law — KCL

KCL is based on conservation of electric charge. At any electrical junction:

ΣI_in = ΣI_out

For the junction used in this experiment:

I₁ = I₂ + I₃

Kirchhoff's Voltage Law — KVL

KVL is based on conservation of energy. Around any closed electrical loop:

ΣV = 0

For a loop containing a source and resistors:

V_source − V_R1 − V_R2 = 0

Ohm's Law

V = IR

Ohm's law is used together with KCL and KVL to determine unknown currents and voltages.

Section 2. Build Your Virtual Circuit

Supply Voltage: 12 V

R₁: 100 Ω

R₂: 220 Ω

R₃: 330 Ω

🟢 Circuit ready. Adjust the values and run the experiment.

Experiment Progress

Section 3. Virtual Circuit

The red node is the junction where the incoming current splits into two branch currents.

Section 4. Virtual Measurement Panel

Main Current I₁ —

Branch Current I₂ —

Branch Current I₃ —

Supply Voltage —

Equivalent Resistance —

Section 5. Verify Kirchhoff's Current Law — KCL

At node A, the incoming current should equal the sum of the outgoing currents.

I₁ = I₂ + I₃

Quantity	Measured / Calculated Value
I₁	—
I₂ + I₃	—
KCL Error	—
KCL Status	—

Section 6. Verify Kirchhoff's Voltage Law — KVL

Consider the left loop containing the supply and R₁. The algebraic sum of voltage changes around the loop must be zero.

V_S − V_R1 − V_R2 = 0

Quantity	Value
Supply Voltage	—
Voltage Drop R₁	—
Voltage Drop R₂	—
Loop Sum	—
KVL Status	—

Section 7. Analysis

Run the experiment to generate the circuit analysis.

Section 8. Student Observation Record

Change one parameter at a time and record at least three trials.

Trial	V_S	R₁	R₂	R₃	I₁	I₂	I₃

Section 9. Experiment Conclusion

Complete and run the experiment to generate the conclusion.

Section 10. Student Quiz

Q1. Kirchhoff's Current Law is based on conservation of: Energy Charge Resistance

Q2. Kirchhoff's Voltage Law states that around a closed loop: The voltage sum is zero The current is zero Resistance is zero

Q3. At a junction, 2 A enters and 0.8 A leaves through one branch. The other branch current is: 1.2 A 2.8 A 0.4 A

Q4. KVL is primarily based on conservation of: Charge Energy Mass

Section 11. CHITTI — 🤖

GARRF Robotics & Engineering AI Mentor

CHITTI can help you understand Kirchhoff's laws, current division, voltage drops and circuit analysis.

💡 Try asking:

"Why must current entering a junction equal current leaving?"

"How does KVL conserve energy?"

"Why does changing R₂ affect the branch currents?"

Section 12. How to Perform This Experiment

Observe the virtual circuit.
Set the supply voltage.
Set R₁, R₂ and R₃.
Predict the branch currents.
Click RUN EXPERIMENT.
Observe I₁, I₂ and I₃.
Verify KCL at the junction.
Verify KVL around the loop.
Change one resistor and repeat.
Record at least three observations.
Complete the quiz.

⭐ Engineering Thinking Challenge

Can you predict the current distribution before the virtual meters display the answer?

If you can predict the result and then verify it experimentally, you are beginning to think like an engineer.

GopalKrishna Advanced Rural Research Foundation

GARRF Virtual Engineering & Electronics Laboratory