Displacement Current Simulation

The Concept

Ampere's Law originally described how electric currents produce magnetic fields. However, Maxwell realized this was incomplete for changing fields, like in a charging capacitor. He proposed that a changing electric flux ($\frac{d\Phi_E}{dt}$) also generates a magnetic field, as if it were a current. This "missing piece" is the Displacement Current ($I_D$).

This concept unified electromagnetism, showing that a changing E-field creates a B-field, and a changing B-field creates an E-field, leading to the discovery of electromagnetic waves.

How to Use the Lab

• Click "Start Guided Tour" for a step-by-step explanation.
• Toggle between DC and AC modes to compare behaviors.
• Adjust the Charging Rate to see how it affects the fields.
• Observe the Conduction Current ($I_C$) in the wires and the Displacement Current ($I_D$) that visually bridges the capacitor gap.
• Notice the Magnetic Field (B) is only created when the Electric Field (E) is changing.
• Use the Waveforms view to see the phase relationship between charge and current.