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Drag a battery, a resistor and some wires here from the left, or load an example circuit.
Drag batteries, resistors, bulbs, switches, meters and wires from the left onto the workspace (or click a card to add one).
Drag a part to move it. Drag a wire end to stretch the wire, or drag from any free terminal to draw a new wire.
When two metal ends touch, a gold contact point appears automatically – that is where current can pass.
Double-click any part to set its properties: battery voltage, resistance, bulb rating, meter range or wire colour.
Click a switch to open or close it. Select a part to rotate or delete it.
Press Start Test on the right. A closed circuit shows the current intensity, moving current dots and every reading.
If the circuit is open, the disconnected spots are marked in red and explained in the list.
| R | rotate selected | Del | delete selected |
| E | properties | Space | flip switch |
| T | start test | Ctrl Z | undo |
| Arrows | nudge | Shift+drag | branch a wire |
Physics: wires, ammeters and closed switches are ideal (0 Ω), voltmeters draw no current, a bulb’s resistance is U² ÷ P. Currents follow Ohm’s law and Kirchhoff’s laws.