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Physics
Charges and fields
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Drag +1 nC or −1 nC charges from the tray onto the board, show the electric field and potential, probe |E|, angle and V, draw equipotential lines with the voltmeter and measure distances with the tape.
2 charges, 0 sensors
More display layers
Drag and keyboard controls
Or drag from the tray under the board. Arrow keys move the selected item (Shift: 1 cm); Delete returns it.
Add a sensor or select an item on the board to read E and V.
−40 V0 V+40 V
Red: positive V; blue: negative V. Colour saturates at ±40 V.
Arrows point along E and get bolder as |E| increases; fully bold from 5 V/m.
Model notes
- Static point charges in a plane; E = kΣq(r − rᵢ)/|r − rᵢ|³ and V = kΣq/|r − rᵢ| with k ≈ 9 V·m/nC (9×10⁹ N·m²/C², rounded as in the original); q = ±1 nC is illustrative.
- Within about 3.2·10⁻⁵ m of a charge centre the original model replaces the sum with a guard value; readings there are reported as too close to a charge instead of a number.
- Equipotential lines are traced with steps perpendicular to E corrected towards V (Newton, RK4 fallback) as in the original; a line that does not close after many attempts stops and is labelled.
- No field lines, forces on charges, conductors or dielectrics; the voltage colour map saturates at ±40 V.