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SCIENCE · INVESTIGATE AND EXPLAIN

Solve node voltages and audit delivered power

Current paths must be defined before writing a matrix. A 6 V source connects to node 1 through Rs. Node 1 connects to ground through 2 Ω and to node 2 through 1 Ω. Node 2 connects to ground through R2. All resistances are positive, constant and lumped; ground is an explicitly chosen zero potential.

Learning outcome: Change R2 while holding Rs fixed. Predict which node and source currents change, then retain both node residuals and the independently calculated power residual. Explain why a zero residual checks arithmetic under this topology but does not verify the topology experimentally.

Starting recap

Review charge continuity, definite integrals, first-order differential equations, initial conditions and signed source work. Distinguish displayed time from physical time.

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Try

For Rs=2 Ω and R2=3 Ω, the equations are 2V1−V2=3 and −V1+(4/3)V2=0. Thus V1=2.4 V and V2=1.8 V. Source current is 1.8 A, bridge current 0.6 A and source power 10.8 W. The four resistor powers are 6.48, 2.88, 0.36 and 1.08 W, also totaling 10.8 W.

Open the experiment

Predict

For Rs=2 Ω and R2=3 Ω, what is the bridge current from node 1 to node 2?

Experiment

Change R2 while holding Rs fixed. Predict which node and source currents change, then retain both node residuals and the independently calculated power residual. Explain why a zero residual checks arithmetic under this topology but does not verify the topology experimentally.

Solve coupled current balances and power

Worked teaching model · synthetic values · Ideal 6 V source to node 1 through Rsource; node 1 to ground through 2 ohm and to node 2 through 1 ohm; node 2 to ground through R2. Constant positive resistances, steady lumped circuit and explicit ground. Virtual only; no source or resistor handling.

Reset keeps your prediction, captures and practice history.

Bridge current for alternative second loads

bridge current (A)second ground resistance (ohm)0510

Unlike graph quantities rescale independently; read units and values, not screen angles. 1: same source-side network (solid). Joined curves show the supplied model, not additional observations.

Equivalent numerical coordinates for Bridge current for alternative second loads

same source-side network

second ground resistance (ohm)bridge current (A)
11
1.050.9836066
1.10.9677419
1.150.952381
1.20.9375
1.250.9230769
1.30.9090909
1.350.8955224
1.40.8823529
1.450.8695652
1.50.8571429
1.550.8450704
1.60.8333333
1.650.8219178
1.70.8108108
1.750.8
1.80.7894737
1.850.7792208
1.90.7692308
1.950.7594937
20.75
2.050.7407407
2.10.7317073
2.150.7228916
2.20.7142857
2.250.7058824
2.30.6976744
2.350.6896552
2.40.6818182
2.450.6741573
2.50.6666667
2.550.6593407
2.60.6521739
2.650.6451613
2.70.6382979
2.750.6315789
2.80.625
2.850.6185567
2.90.6122449
2.950.6060606
30.6
3.050.5940594
3.10.5882353
3.150.5825243
3.20.5769231
3.250.5714286
3.30.5660377
3.350.5607477
3.40.5555556
3.450.5504587
3.50.5454545
3.550.5405405
3.60.5357143
3.650.5309735
3.70.5263158
3.750.5217391
3.80.5172414
3.850.5128205
3.90.5084746
3.950.5042017
40.5
4.050.4958678
4.10.4918033
4.150.4878049
4.20.483871
4.250.48
4.30.4761905
4.350.4724409
4.40.46875
4.450.4651163
4.50.4615385
4.550.4580153
4.60.4545455
4.650.4511278
4.70.4477612
4.750.4444444
4.80.4411765
4.850.4379562
4.90.4347826
4.950.4316547
50.4285714

At most 82 representative computed coordinates including endpoints; the plotted curve can use a finer grid. A table of a revealed generator is not independent measurement evidence.

Calculated quantities under the declared measurement model
QuantityValueUnit
First node potential2.4V
Second node potential1.8V
Source current1.8A
Bridge current from node 10.6A
First-node current residual-4.44089e-16A
Second-node current residual0A
Source power delivered10.8W
Total resistive conversion10.8W
Power residual0W

Node equations enforce local charge continuity and the separate power sum checks the signs.

The conductance matrix is [(1/Rs+1/2+1),−1;−1,(1+1/R2)]. Multiplying by the node-voltage vector gives [6/Rs,0]. Currents use potential differences divided by their own resistances. The voltage-source delivered power equals the sum I²R over all four resistors. No accumulation occurs in this stipulated steady state; it does not justify ignoring capacitive charge during a switch.

Predict before inspecting the values. Save contrasting records with assumptions and one alternative explanation. This virtual display does not certify practical measurement technique.

Node equations enforce local charge continuity and the separate power sum checks the signs.

The conductance matrix is [(1/Rs+1/2+1),−1;−1,(1+1/R2)]. Multiplying by the node-voltage vector gives [6/Rs,0]. Currents use potential differences divided by their own resistances. The voltage-source delivered power equals the sum I²R over all four resistors. No accumulation occurs in this stipulated steady state; it does not justify ignoring capacitive charge during a switch.

Captures preserve recipes and replay their calculated results. They are synthetic model evidence, not physical measurements.

Understand

State the current, source and measurement model

Current paths must be defined before writing a matrix. A 6 V source connects to node 1 through Rs. Node 1 connects to ground through 2 Ω and to node 2 through 1 Ω. Node 2 connects to ground through R2. All resistances are positive, constant and lumped; ground is an explicitly chosen zero potential.

Derive the integral or initial-value solution

Current balance at node 1 gives (6−V1)/Rs=V1/2+(V1−V2). At node 2, V1−V2=V2/R2. Rearranging yields a symmetric conductance matrix with diagonal entries 1/Rs+1/2+1 and 1+1/R2, and off-diagonal entries −1. Solve for both potentials, then reconstruct each branch current.

Test conservation, uncertainty and limits

The delivered source power is 6 times its outgoing current. Independently sum I²R over all four resistors; the two powers must agree. This is more discriminating than checking one node alone. The steady balance contains no charge accumulation, and therefore cannot automatically describe the moment a capacitor or inductor is switched.

Worked original case

For Rs=2 Ω and R2=3 Ω, the equations are 2V1−V2=3 and −V1+(4/3)V2=0. Thus V1=2.4 V and V2=1.8 V. Source current is 1.8 A, bridge current 0.6 A and source power 10.8 W. The four resistor powers are 6.48, 2.88, 0.36 and 1.08 W, also totaling 10.8 W.

Investigation

Change R2 while holding Rs fixed. Predict which node and source currents change, then retain both node residuals and the independently calculated power residual. Explain why a zero residual checks arithmetic under this topology but does not verify the topology experimentally.

Changed-case practice

Try the changed case before feedback

For Rs=1 Ω and R2=1 Ω, find node 2 voltage in volts.

This practice is public and unsaved. A matching number does not verify understanding. Retain your explanation, assumptions and changed-case evidence in the separate course workspace.

Sources and boundaries

Original derivations and synthetic evidence checked 31 October 2026 against the primary explanation. No live circuit construction, energized switching, component rating or electrical handling instruction is requested. Preserve first predictions, critique, revision and fresh assigned work separately from public practice. Software agreement does not certify measurement technique or learning.

Apply

For Rs=2 Ω and R2=3 Ω, what is the bridge current from node 1 to node 2?

Public practice checks a specific claim. It does not establish independent mastery.

Which initial state, calibration or constitutive assumption is needed for this conclusion, and what fresh evidence could test it?

Continue

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