The acceleration of electrons in an antenna rod produces a radio wave with its oscillating electrical and magnetic fields.

For a vertically oriented rod the electric field points up- and downwards. If at one moment the electric field points upwards, the magnetic field points to an orthogonal direction and this could be either to the right or to the left (but nether to both at the same time because in this case a loop antenna wouldn’t work).
The pointing to the left or to the right magnetic field component could be described by the left or the right hand. Be the thumb the direction of propagation of the wave and the second finger the electric field at one moment, the third finger points into the direction of the magnetic field.

For which subatomic particles (proton, positron and antiproton) does the magnetic field - under the same conditions - point in the same direction and for which is it antiparallel?

  • $\begingroup$ As an aside, in the context of electromagnetic radiation, "left-handed" and "right-handed" generally refer to circular polarization and not to the (fixed!) relationship between the direction of the electric and magnetic fields. That is it related to the change seen in the direction of the electric field (the direction of the magnetic field also changes in lock-step but by convention we use the electric field as the indicator) over time. $\endgroup$ Sep 5, 2019 at 15:50
  • $\begingroup$ @dmckee But it describes perfectly the situation. Taking the thumb as the direction of propagation and the second finger as the electric field component, the magnetic field can be described with the third finger of the left or the right hand. $\endgroup$ Sep 5, 2019 at 16:14
  • $\begingroup$ It would be an appropriate description if the issue ever came up. But it is also appropriate to circular polarization and that actually comes in both varieties. So the phrase is understood to refer to the thing that actually varies. $\endgroup$ Sep 5, 2019 at 16:30
  • $\begingroup$ @dmckee I’ve tried to avoid in my question the left hand and right hand analogy $\endgroup$ Sep 6, 2019 at 6:59

1 Answer 1


The geometric relationship between $\vec{E}$ (electric field), $\vec{B}$ (magnetic field) and $\vec{S}$ (the Poynting vector associated with the wave) in free space is set by Maxwell's equations. It doesn't depend on the source at all.

In situation that are not purely free-space (in the near field or in a wave guide for instance) the boundary conditions can affect the situation.


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