Field lines are traced in true 3D by integrating the vector field E = k·q·r̂/r² away from every positive charge, exactly as Coulomb's law predicts — just no longer flattened to a plane.
Positive (+)
Negative (−)
Probe (test charge)
Add Charge
Field Lines
Field strength
E = k · q / r²
The green probe sphere is a movable unit test charge — drag it anywhere in 3D to read the local field and the force it feels, live.
Probe readout
|E|0.00
Ex, Ey, Ez0, 0, 0
Force (q·E)0.00
Charges0
🖱️ Click empty space — add charge | Drag a sphere — move it | Drag background — orbit | Scroll — zoom