Split 5 V with two resistors
Begin with 1 kΩ + 1 kΩ. Predict 2.5 V at VOUT and 2.5 mA through the top resistor. Change the lower resistor to 2 kΩ: what changes?
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Change a resistor, watch a capacitor charge, and compare the simulator’s actual readings with a calculation. Keep the native circuit and your lab notes to revise later.
No account. No upload. No automatic saving. This local teaching edition uses CircuitJS 5.0.4. It supports nine primitive component types, not the full upstream editor.
Start with a useful experiment
Watch a one-second time constant
Charge 100 µF through 10 kΩ from 5 V. At one time constant, predict about 3.16 V. Double the resistor and compare the slower rise.
Educational, idealized models only. Not electrical safety advice or validation for mains power, batteries, medical devices or physical construction.
1. Open or revise a circuit
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Preview applies your draft and resets to its authored initial capacitor voltage / inductor current, starting at t = 0. Saved instantaneous values are preserved in the draft, not resumed. Changing a component clears the old run.
2. Run and measure
The diagram is an original read-only schematic of your circuit; CircuitJS provides the actual solver. Edit components above, then preview. For the lesson resistors, positive current flows from the first endpoint to the second. Voltage-source polarity follows CircuitJS’s source convention, described with the readings.
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Actual engine readings
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Calculated reference
A reference is shown only for the two unchanged lesson topologies. It is calculated separately, never inserted into the actual readings.
Recorded observations
Samples come from CircuitJS after actual solver steps, at about 0.1 seconds of simulated time. A downloaded worksheet preserves them as historical data, not a resumable simulation checkpoint.
Native XML keeps component settings and some instantaneous state; it does not restore elapsed simulation time. Reset uses initial capacitor voltage / inductor current. Reopen and rerun to verify a saved circuit.
3. Keep a lab notebook
The JSON worksheet contains native circuit XML, your notes and recorded values. Reopen it here. Saved observations are labelled historical and must be rerun for a new result. Nothing is stored automatically.
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Do you need a paid circuit lab for this lesson?
For a small resistor-divider or RC transient experiment, this page provides real circuit solving, voltage/current readings and editable native files without an account or paid desktop lab.
- Here: R/L/C, wire, ground, DC or periodic voltage sources, current sources, named nodes and simple switches; fixed 1 ms time step; up to 128 components; actual per-component voltage and current; native save/reopen and local worksheets.
- Where paid desktop software such as Multisim can go further: larger component libraries, instrument workflows, analyses and integration beyond this teaching subset. This page is not a Multisim file converter, SPICE netlist tool, PCB designer or professional hardware verification suite.
- Also compare free choices: upstream CircuitJS has a much broader visual editor; LTspice and KiCad may already cover your needs. No savings or numerical-equivalence claim is made. This comparison concerns desktop Multisim, not the discontinued Multisim Live service.
Multisim’s official product description (documentation reviewed 7 November 2026, not hands-on competitor testing) · Upstream CircuitJS
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Download exact corresponding source and rebuild files · Licenses and credits · Build and verification notes
Verified 7 November 2026: 82 adapter tests, 13 analytical tests, 29 real-engine fixtures, and desktop Chromium divider/RC edit, download and fresh-reopen workflows. Narrow-screen/mobile, screen-reader, real-beginner and hardware use were not verified. No full network capture or security certification is claimed. See the build notes for exact coverage.