Visualizing the Invisible: Electric Field Lines
Electric fields are invisible, but we can map them using field lines — a concept introduced by Michael Faraday in the 1830s. Each line shows the direction a positive test charge would move if placed at that point. The density of lines indicates field strength: closely spaced lines mean a strong field, widely spaced lines mean a weak field.
Coulomb's Law and Point Charges
The electric field around a point charge follows Coulomb's law: E = kQ/r². A single positive charge creates field lines radiating outward in all directions. A single negative charge has lines pointing inward. The inverse-square falloff means the field drops rapidly with distance — doubling the distance reduces the field to one quarter.
Dipoles and Charge Configurations
When two opposite charges are placed near each other, they form a dipole. Field lines curve from the positive charge to the negative charge, creating the characteristic dipole pattern seen in this simulation. Like charges create a repulsive pattern with a neutral point between them where the field is zero. More complex arrangements produce intricate field patterns.
Equipotential Lines and Energy
Perpendicular to the field lines are equipotential lines — contours of constant electric potential. Moving a charge along an equipotential requires no work, just like walking along a contour line on a topographic map. The voltage difference between equipotentials determines the energy gained or lost by a charge moving between them.