Explore the Circuit Lab
Wire two resistors in series or parallel and see voltage, current and power. Free, no signup, runs in your browser.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
See it in action
The Circuit Lab with sample data entered and the result showing.
What is the Circuit Lab?
Wire two resistors in series or parallel and see voltage, current and power. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
Every electronic device is a circuit. Electricians, engineers and hobbyists use series and parallel rules to size resistors, fuses and wiring.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Ohm's law: V = I × R.
In series the current is the same everywhere and resistances add: R = R1 + R2.
In parallel the voltage is the same across each branch and 1/R = 1/R1 + 1/R2.
Switch between series and parallel with the same resistors.
Raise the voltage and watch the current and power rise.
Make R1 very small in series and see where the voltage drops.
Used for
Pick one to see how it fits.
Physics learners
Physics students in middle school, high school and first-year university, teachers who want a quick demonstration for the projector, and anyone revising for exams.
Try it freeTeachers
For teachers: project the Circuit Lab (Ohm's Law) on the board, let students predict the result, then run it together and test this: Raise the voltage and watch the current and power rise. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
What is the difference between series and parallel circuits?
In a series circuit there is one path, so the same current flows through every part. In a parallel circuit the current splits between branches, and each branch sees the full battery voltage.
Why does total resistance go down in parallel?
Each extra branch gives the current another path, so overall it is easier for charge to flow. The total is always smaller than the smallest branch.
Is the Circuit Lab (Ohm's Law) free to use?
Yes. The Circuit Lab (Ohm's Law) is free, needs no signup or download and runs in your web browser. It is part of the Physics group of AZRS simulations.
Does the Circuit Lab (Ohm's Law) work on a phone or tablet?
Yes. The Circuit Lab (Ohm's Law) takes touch input as well as mouse input, so you can use its 4 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Circuit Lab?
1. In the Circuit Lab (Ohm's Law), use the controls to change Wiring, Battery voltage, Resistor R1, Resistor R2. The simulation reacts instantly. 2. In the Circuit Lab (Ohm's Law), pick an option such as Series, Parallel to switch modes or load an example. 3. Start with this experiment: Switch between series and parallel with the same resistors. Drag any glowing handle, object or slider with your mouse or finger and the Circuit Lab (Ohm's Law) responds in real time. 4. Change one setting at a time and watch which readout moves, then compare it with this idea: Ohm's law: V = I × R.
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Try the Circuit Lab now
Wire two resistors in series or parallel and see voltage, current and power. Free to use.
Try it free