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E&M Field Explorer

Learning goal

Make electric fields tangible: field lines leave positive charges and land on negative ones; where lines crowd, \(|\vec E|\) is large; the potential (background shading) is high near positive charges and its steepest descent is the field.

Things to try

  1. Dipole preset — compare near-field (loops from + to −) with far-field (looks like a weak single charge... but falls as \(1/r^3\): electric dipole).
  2. Like pair — find the dead spot between them where \(\vec E = 0\), and notice no field line passes through it.
  3. Build a "capacitor" — a row of + above a row of −: watch the field become uniform between and weak outside, exactly the parallel-plate idealization.
  4. Count line endings — lines per charge is proportional to \(|q|\); that bookkeeping is Gauss's law.

Electric field · Electric potential · Gauss's law · Equipotential surfaces