Laboratory / Physics
Fields, models, and limits
Place positive and negative sources on a plane and sample the resulting vector field. Compare individual contributions with their vector sum and inspect where cancellation occurs.
What changed
Charge strength 5 and separation 35 change every local vector. The arrows sample a continuous field; they are not physical threads.
Return to the route
Experiment after prediction.
Before changing a control, say which visible feature should move and which should remain invariant. That prediction is the useful part of the experiment; motion alone is not evidence.