Physics · Class 12

Kirchhoff junction and loop rules

One series resistor feeds two parallel branches. Changing one branch changes the node voltage and both branch currents. The readout verifies charge conservation at the junction.

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Kirchhoff junction and loop rules

சந்தியில் வரும் மின்னோட்டம் வெளியேறும் மின்னோட்டங்களின் கூட்டுத்தொகை. மூடிய சுற்றில் மின்னழுத்தங்களின் கூட்டுத்தொகை பூஜ்யம்.

Key notes, relationships and model limits

Key relationship

I₁=I₂+I₃; ε−I₁R₁−I₂R₂=0; I₂R₂=I₃R₃.

Remember

One series resistor feeds two parallel branches. Changing one branch changes the node voltage and both branch currents. The readout verifies charge conservation at the junction.

Common trap

Choose current and loop directions consistently. A negative answer means the actual current is opposite to the assumed direction.

Model limits

An ideal DC source feeds one series resistor and two parallel branches with fixed resistances. The panel checks this circuit topology rather than solving an arbitrary circuit.

What you will learn

Use the controls and plotted relation to explain kirchhoff junction and loop rules.

Try the experiment

Try both scenarios, change one control, and predict the result before checking the graph and readouts.

Think of it this way

Change one input while keeping the others fixed, as you would in a controlled experiment.

Worked example

For ε=12 V, R₁=10 Ω, R₂=20 Ω, R₃=30 Ω, I₁=0.545 A, I₂=0.327 A and I₃=0.218 A.

Why this matters

The model connects kirchhoff junction and loop rules with an observable reading. Check the equation and assumptions before applying it.

Before you start

SI units · algebra · graph reading

Check your understanding

Kirchhoff junction law follows from conservation of?

Mechanical momentum only.
Electric charge.
Voltage being identical in every circuit branch.

Read the explanation

Electric charge.

Course connection: Class XII Chapter 3. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.