Electromagnetism · Liénard–Wiechert fields, solved per pixel on the GPU

EM Field Lab — Electromagnetic Fields, Radiation & Retarded Potentials

Nothing in a field travels faster than c. An interactive electromagnetic field lab exploring moving charges, retarded effects, E and B fields, Poynting flow and propagation at the speed of light.

the charge field that has heard the news · points at where the charge is field that has not · still points at where it was the kink · news of the kick, expanding at c
The whole lab in one picture. Kick a charge and the field does not update everywhere at once. A shell of kinked field lines leaves the old position at c; inside it the field has caught up, outside it the field is still the field of a charge that no longer sits there. That shell is the radiation, and it is the only part that falls off as 1/R.

Probe—
Total E—
Radiated part—
Bz—

Energy flux

P radiated
—
line integral
—
peak lobe
—

Time-averaged. The polar plot is outward flux against angle; the dashed circle is zero.

Probes

Two probes at different distances let you measure c from the delay between them.

source
—
path difference
—
measured delay
—
c from delay
—

Wheel zooms · shift-drag pans · double-click adds a charge

Continue exploring
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