Is Maxwell's theory of electromagnetism completely validated?

Question

Most of the time, I read articles or watch videos saying that Hertz experiments validated Maxwell's theory of electromagnetism. But Hertz only confirmed the existence of waves (that are perhaps electromagnetic) and that they travel at the speed of light.

He did not for example confirm that these waves have both an electric and magnetic components. Although we know that the spark generated at the receiver of his apparatus is due to electromagnetic induction (changing magnetic field that produces current), we don't have evidence about the electric component.

Is there any experiment that confirms there is an electric component of these waves?

Answer 1

A linear dipole antenna (thickness << length AND thickness << wavelength) is sensitive to the electric field of the EM wave, a circular loop antenna (thickness << diameter AND thickness << wavelength) is sensitive to the magnetic field of the EM wave.

Answer 2

Is there any experiment that confirms there is an electric component of these waves?

How electromagnetic radiation takes place

The source of EM radiation are the subatomic particles. They absorb and emit photons. Another method does not exist. Hence radiation consists of photons.

A simple method to stimulate EM radiation is to accelerate and decelerate electrons. This was done in electric bulbs. The emitted radiation was over a wide spectra form infrared to visible light.

How to generate EM waves

Accelerating electrons periodically forth and back EM radiation in the form of an EM wave will be emitted. Installing an second antenna rod, best in the same direction as the emitting rod, the photons will induce an electric current (an alternating current) in the rod. This current is measurable.

Installing a loop antenna, the photons magnetic field will induce a current in the loop.

The orientation of the magnetic to the electric field

It‘s obvious that the acceleration of photons, all in the same direction, induces the electric field component of the emitted photons all in the same direction. Otherwise it would be impossible to get a current on the receiving antenna. And the same holds for the magnetic field component.

Holding your thumb up - representing the current in the antenna rod -, your second finger of the right hand shows the direction of the magnetic field component. Or should you take the left hand?

That does not matter as long, as you do not choose, should your finger show the north south direction or the S N direction. Once defined, the empirical facts show, that both field components from the electrons radiation always follows the same chirality. Only this allows as to have magnetic loop antennas.

Long story short. EM radiation consists of photons. The electric field and the magnetic field of these photons is nit measurable due to the chaotic emission. In the special case of synchronous radiation we get an EM wave (radio wave) and the macroscopic field components are measurable.

Answer 3

Maxwell's theory has been validated by the entire body of physics since publication.

Specifically, nearly all light absorption is due to electric dipole interaction, while paramagnetic resonance such as EPR, MRI and the astronomical 21 cm line are magnetic dipole transitions.

Answer 4

It is easy to show, using the Lorentz force, that the work done per unit of volume and time on free charges by EM plane waves is $W = \mathbf {E.J}$, where $\mathbf E$ is the electric field of the wave and $\mathbf J$ is the density of current. The magnetic field contribution for the Lorentz force cancels out, and doesn't contribute for the work.

Every actual receptor circuit has resistance and it is necessary power to generate currents on them. As far I as understand we could not have that dissipated power in the circuit without the electric component of the wave.

Answer 5

I think the issue here is in understanding what does it mean "electric" and "magnetic"; what actually are these fields? Strange they are in the space and time but they are not spacetime. Is it strange for you? For me it is absolutely outstanding!

I think that with his equations Maxwell wanted to say that even if these two fields are different in a way, they are strictly interlaced. To try to answer your question, consider that applying some logic passages starting from the Maxwell equations, you obtain the Poyting theorem that states that the change in energy density in a point of space and time, depends on the presence of charges and the Poynting vector.

If you are in empty space without net physical charges, you remain with the Poynting vector, in which electric and magnetic field cannot be everywere simultaneously null, if you have a process with energy exchange; radiation is this kind of process so that explains why the two fields are both present and interlaced.

This is just the theory, talking about an experiment, consider that Maxwell arrived to these equations trough a lot of experiments, but I don't have any of them in mind, someone can surely argument them very well.