Just below the figure you drew of the tilted Wiener plate, you said: “But, because of the complementary behavior of the electric and magnetic fields, the magnetic field must have a maximum at the surface!” If there is a temporary release from the requirement to be in-phase when in the vicinity of a boundary, what is the mechanism that puts them back in phase? How long (how far from the mirror) before they are back in phase?

Walt

The trick here is that we’re talking about perpendicular fields, and there are really two different ways in which we can talk about the phase relationship being “0 degrees”. The proper statement is more along the lines of, “The E and H fields reach an extreme value of amplitude and a minimum value of amplitude at the same point in time and space.”

To try and put it more clearly: an electromagnetic plane wave satisfies a “right-hand rule” with respect to the E-field, H-field, and direction of propagation. That is, let you index finger point in the direction of E, fold your middle finger inward to represent the direction of H, and your thumb should point in the direction of motion.

Let’s suppose that a wave is impinging on a mirror in the +z direction (thumb points towards +z). Upon reflection, the wave is now traveling in the -z direction, and your thumb should also point in the -z direction. In order for this to happen, one of two things must happen: you either twist your hand around your index finger (E-field is unchanged) or you twist your hand around your middle finger (H-field is unchanged). In other words, when a wave is reflected, either the E-field or the H-field must change sign (or change phase by 180 degrees). Physically, we know that the total E-field must be zero at the surface of a conductor, so the E-field changes sign at the surface.

This is why the anti-nodes of E and H are in different places: the E-field changes sign upon reflection, while the H-field does not. The relative phase between the incident and reflected E-fields is therefore different from the relative phase between the incident and reflected H-fields.

(This is all much easier to see when writing it out in equations.)

The original experiment demonstrated that what reacts with a photographic emulsion is the E-field rather than the H-field. But with a loop and a monopole antenna I can demonstrate something more fundamental; that E and H have anti-nodes in different places. The reason they are different is because in one case the reflection is in phase and in the other, 180 out. (In the figure you drew above, there’s a shift of 90 degrees. Is that a mistake?) When a reflected wave mixes with the incident wave, there is a standing wave anti-node every half wavelength regardless of how it starts. But how it starts is the most important thing in the Wiener Experiment. This is the part I cannot picture. If you enter “standing waves” in Google the vast majority of hits are of the wiggling-rope figures that have the reflection terminated in which case the first anti-nodes is 1/4 wave away. I could find no example where the rope was held loosely and tightly on the same diagram. But there’s an excellent animation of an open reflection of an acoustic wave of an open end standing wave. That website is..
http://www.phys.unsw.edu.au/jw/strings.html
It shows clearly that the first anti-node is one quarter wavelength out. Wait a minute. Maybe this is a closed end reflection. Check it out if you would. It is very well done but maybe they made a mistake.
What’s important is the phase of the standing waves and I think it can be accepted that they are different for open and closed reflections. The first measurable one in one case is 1/4 wave away from the mirror and the other 1/2 wave away. I’m not clear whether E-reflection anti-node is 1/4 wave or 1/2 wave. But that isn’t my biggest confusion. What really bothers me is the tradition every physics student has accepted on faith for over a hundred years. And that is that the phase relationship between E and H is 0 degrees. If that’s the case, how can there be an anti-node for E and H in different places? And if they are only temporarily out of phase, what brings them back and how long does it take for them to come back together?

Ah, I see!

I tend to write only one major physics/optics post a week, because they take a lot of time to write and I’ve still got to do my paying job! If you were looking only at the most recent posts, you might not have gone back far enough to see my more recent physics posts. Try the optics tag or the physics tag to get a direct list of my scientific descriptions.

As for your more technical question, let me give it a few days’ thought…

You were very quick to agree with Andrew Geng on the phase relationship between E and H in a traveling wave. I do not understand the math that claims these two are in phase; and many a teacher has tried. Even if I did, I’d prefer actual measurement. In attempting to do so I have observed (with with loop on one input of a scope and vertical antenna on the other) that at 72 MHz they are in quadrature in the near field and out to 5 or 6 wavelengths. I can’t measure farther than that because the environment is too noisy. Normally one uses amplifier and a tuned circuit but I don’t want to use tuned circuit because that changes the phase.
Do you have any suggestions for demonstrating or understanding this relationship?

Well, thanks!

“I was rather hoping I could see other works of physics with such clarity of explanation on your website. But it is all housewife stuff.”

??? Um, what are you talking about? If you’re referring to the rather non-mathematical explanations on other posts, that’s what I’m shooting for these days: posts which describe physical phenomena in non-technical terms for a broader audience. I’m leaving the ultra-technical descriptions for the research journals. I’m happy to field questions in the comments, though.

By the way, I’ve done this experiment at 144 MHz at 28MHz and working on an X-band version of it.

I am particularly interested in discussing the phase relationship between E and H which Andrew Geng brought up.