Practice question · Multiple choice
Bound currents in magnetised matter are real microscopic currents, yet they transport no net charge across macroscopic distances. Why does this distinction prevent bound current from appearing in the curl of the auxiliary field H?
Hints
- Which currents can an experimentalist directly adjust with a power supply?
- Does the auxiliary field D in electrostatics account for bound polarisation charges?
Show the answer
A. Auxiliary fields track only controllable external flows
Why
Microscopic bound currents generate genuine B-fields and obey continuity, but they cannot be routed or metered externally. Defining H isolates the engineer's transport currents from material response.
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