Resistor Circuit Lab: Compare Series and Parallel

Connect two resistors in series or parallel. Compare resistance, current, voltage, and power with an ideal battery.

Free, with no sign-up.

For High school students and adults reviewing the topic.

About 8 minutes.

How does it work?

  1. Change a control to update the table and diagram.
  2. Open a preset to compare settings, then try the challenges.

What will you get?

Compare the model’s outputs, explore its presets, and check two challenges.

What does the model assume?

  • The battery maintains the chosen EMF with zero internal resistance. Wires and connections have zero resistance.
  • Both resistors are ohmic and keep their selected resistance at every setting. Heating does not change their values.
  • The model describes a steady direct-current circuit. Charge does not accumulate at junctions, and delivered power equals total resistor power.
  • Values are illustrative. The diagram is a model, not instructions for household wiring.

Which setup would you like to try?

What can you change?

Range: 0 to 24 V.

Range: 1 to 100 Ω.

Range: 1 to 100 Ω.

What does the model predict?

QuantityValueUnit
Equivalent resistance12.000Ω
Total current1.000A
First resistor current1.000A
Second resistor current1.000A
First resistor voltage4.000V
Second resistor voltage8.000V
First resistor power4.000W
Second resistor power8.000W
Total power12.000W
Two-resistor circuit
R₁: 4 Ω4 V; 1 AR₂: 8 Ω8 V; 1 ABattery: 12 V

Rectangles represent resistors. Lines show connections; labels give the calculated voltage and current.

Series connection: total current 1 A. The first resistor has 4 V and 1 A; the second has 8 V and 1 A.

Can you reach these targets?

Use a 12 V battery and a first resistance of 4 Ω in series. Choose the second resistance for a total current of 1 A.

  • Target: Battery EMF = 12 V; tolerance 0 V.
  • Target: First resistance = 4 Ω; tolerance 0 Ω.
  • Target: Total current = 1 A; tolerance 0.001 A.
  • Connection (Series)

Keep 12 V, 4 Ω, and 8 Ω. Choose the arrangement that dissipates 54 W.

  • Target: Battery EMF = 12 V; tolerance 0 V.
  • Target: First resistance = 4 Ω; tolerance 0 Ω.
  • Target: Second resistance = 8 Ω; tolerance 0 Ω.
  • Target: Total power = 54 W; tolerance 0.001 W.
Read the topic guide