Mr Moorthy.  You have completely the wrong idea about electromagnetic waves.  Electromagnetic waves at all frequencies (and wavelengths) have both magnetic and electric fields.

Gamma rays, x rays, ultra-violet rays, visible light, infra red, terahz, millimetre, microwave, UHF VHF HF and low frequencies, even 50 Hz and below, all have magnetic and electric fields as described by Maxwell's equations.  These can be measured (don't know if this is true at frequencies above infra-red), but as Mr Fricke has said, the measurement methods often depend on the truth of Maxwell's equations so unless one is careful about which method to use one may not prove to one's own satisfaction that both fields exist.

It is only in the case of DC or unchanging fields where magnetic or electric fields can exist by themselves.

It is like asking whether there are sound waves that only have movement of molecules, and not changes of pressure, or whether there are sound waves that have changes of pressure and not movement of molecules.  The two are inseparably linked.  The movement of molecules towards a place results in an increase of pressure there, and that pressure then results in movement of molecules.

Changing electric fields result in magnetic fields.  Changing magnetic fields result in electric fields.  Maxwell's equations show how these are linked and can form waves.  The equations predict a speed for these waves, and that is the same as the speed of light, which was a major triumph for Maxwell.

In a vacuum, an electric field cannot directly induce another electric field so a "pure" electric field wave cannot exist.  The same can be said for a "pure" magnetic wave.  Maxwell's equations quantifies how a time-varying electric field induces a magnetic field and how a time-varying magnetic field induces an electric field.  It is this interaction that causes waves.  For this reason, both electric and magnetic fields must exist if a wave is being observed.

At low frequencies, the two components can be detected separately to prove they do both really exist.

Thanks Professor Raymond Rumpf.  Is there any article which specifies that both field waves with a common wave length were observed?

If I understand the question correctly, the measurement of the magnetic field has to be a "direct" one. Usually, magnetic field sensors measure the curl of the E field, and since one of the Maxwell equations is curl E = -d B / d t, one can calculate the B field (except for a constant) from the result. But doubting that the E component of a radiation field is accompanied by a B component boils down to doubting the general applicability of the Maxwell equation mentioned above, and consequently the function of these indirect magnetic field sensors has to be doubted, too.

Fortunately, there are magneto-optical sensors based on the Faraday effect which seem to respond not only to magnetic fields in the low frequency domain but to the B component of radiation fields up to some THz, too (please see the article below). The experimental results show that THz radiation contains a magnetic field; admittedly, since the measured signal is similar to that of a demodulator probe, it does not reveal the frequency and phase of the B field. However, the only alternative to accepting the Maxwell equation on curl E seems to be to assume that at high frequencies the E component of the radiation has a similar effect on optical crystals as the B field at low frequencies, and such an assumption had a hard stand against Occam's razor, I guess.

Article Free-space transient magneto-optic sampling

 I like to  thank Professor Joerg Fricke for providing an article.  His answer is too much technical to me.  I have no idea of sensors.  I also did not like to contradict  Maxwell equations.  My question was based on non-mathematical support for wave propagation from solutions of wave differential equations.  My expectation is that sensors should predict two orthogonal waves, perhaps one by means of a wire coil and one by means of semiconductors of solar cells.   Indirect methods may also be applied to predict two orthogonal waves. Since some THz waves are obtained from black body radiation, from the article mentioned by Prof. Joerg Fricke, I guess that there should be a wave length, say K, in the spectrum of THz waves such that all EM waves with wave length less than K should be free from magnetic field, and all EM waves with wave length greater than K should be free from electric field.

Mr Moorthy.  You have completely the wrong idea about electromagnetic waves.  Electromagnetic waves at all frequencies (and wavelengths) have both magnetic and electric fields.

Gamma rays, x rays, ultra-violet rays, visible light, infra red, terahz, millimetre, microwave, UHF VHF HF and low frequencies, even 50 Hz and below, all have magnetic and electric fields as described by Maxwell's equations.  These can be measured (don't know if this is true at frequencies above infra-red), but as Mr Fricke has said, the measurement methods often depend on the truth of Maxwell's equations so unless one is careful about which method to use one may not prove to one's own satisfaction that both fields exist.

It is only in the case of DC or unchanging fields where magnetic or electric fields can exist by themselves.

It is like asking whether there are sound waves that only have movement of molecules, and not changes of pressure, or whether there are sound waves that have changes of pressure and not movement of molecules.  The two are inseparably linked.  The movement of molecules towards a place results in an increase of pressure there, and that pressure then results in movement of molecules.

Changing electric fields result in magnetic fields.  Changing magnetic fields result in electric fields.  Maxwell's equations show how these are linked and can form waves.  The equations predict a speed for these waves, and that is the same as the speed of light, which was a major triumph for Maxwell.

Dear Professor Malcolm White

"Changing electric fields results in magnetic fields.  Changing magnetic fields results in electric fields.  Maxwell's equations show how these are linked ".  I agree completely with these statements, and I also agree with the last statement " The equations predict a speed for these waves, and that is the same as the speed of light, which was a major triumph for Maxwell."  It is an unexpected breakthrough which should always celebrated.  My claim is that both electric field waves and magnetic waves do not get propagated simultaneously, but both fields may change simultaneously, as you said.  Variation in the fields is not sufficient for propagation.

Mr Moorthy

I suggest you read the pages leading up to 443 in Electromagnetic Waves by Carlo G. Someda (Second edition), if you can access it.  It explains how, if the radiators are much smaller than a wavelength, the propagating fields are insignificant everywhere, compared to the inductive fields, and it appears that magnetic and electric fields exist independently.  However this is an approximation, and propagating fields do exist and the waves contain electric and magnetic fields in the expected ratio (the impedance of free space).

In the presence of conductors the electric and magnetic fields can be localised to different regions of space, but this represents stored power, not propagating power.  Propagating power requires both in the same region of space, in the form of a wave described by Maxwell's equations.

Dear Professor Malcolm White

I like to thank you and Prof. J. Fricke for your contributions in explaining the concept. The exact words in the book suggested by you are the following:"it is well known that static or

slowly-varying electric fields appear to be independent of magnetic ones, and

vice-versa. Our approach shows that this apparent independence is, in reality,

the result of an approximation which is acceptable only if one can neglect

delays due to the finite velocity of propagation of e.m. waves."

Your explanation suggests that one field variation may have enough power for wave propagation, when the other field variation may not have enough power for wave propagation.  The energy distribution and power distribution between the two fields may be like this: One gets more and the other gets less.  

In connection with the article Prof. J. Fricke, I refer to the figure given in the article suggested by the professor.  You may find a polarizer in the figure. Polarizers may filter electric field waves  or orthogonal  magnetic field waves  when EM waves pass through them. This itself suggests production of separate electric field waves as well as separate magnetic field waves, and thereby there is a suggestion for existence of such waves.  

I like to thank both of you for giving strength to a proposed observation in my article.  

Dear Prof. C. Ganesa Moorthy,

in an earlier response your wrote that you do not intend to doubt the correctness of the Maxwell equations. From these equations, the Poynting vector S can be directly derived:

S = E x H

with the vector E for the electric field, the vector H for the magnetic field, and the vector S for the density of power flow, "x" being the vector product resp. cross product. Except for gravitational waves, S describes the only way energy can flow in vacuum (= space without any particles with non-zero rest mass).

As a consequence, static electric and magnetic fields, which are a form of non-moving energy, can exist separately. Changing resp. propagating EM fields are inevitably connected with a power flow, and a non-zero power flow can exist only if both an E and a H field are present, according to the Poynting vector.

If an EM wave could exist with E field and H field in separate frequency bands (as you suggested earlier) there would be power flow both in forward and in backward direction, the integral of the power flow over one period of time converging everywhere to zero, i. e. the energy would not propagate but just oscillate forward and backward. (This is what happens partly in the near field of radiation sources but not due to different frequencies but due to differences in phase.)

If you would succeed in stripping a propagating EM wave of its E field or of its H field you would get a wave "frozen" in space (not to be confused with a "standing" wave). Up till now, such a phenomenon has never been observed, and its existence would shake the foundations of physics. (E. g. a linearly polarized beam, frozen in space because stripped of its H field, and traversed by charged particles, would yield the first really working perpetuum mobile. :-)

When a wave is reflected by a polarizing grid (or any polarizer I have come across - such as a dielectric boundary at the Brewster angle) the magnetic field part of the wave is reflected at the same time as the electric part.  If the electric part of the wave is not reflected, neither is the magnetic part.  There is no separation of magnetic and electric parts of the wave.  The polarizer does not separate electric from magnetic waves, but electromagnetic waves of one polarization from electromagnetic waves of perpendicular polarization.

Dear professors J. Fricke and M. White

I like to repeat my logical argument, in a different way.  My observation was that there is no EM wave having two component waves.  That  is EM waves have only one type of component waves.  So, there are waves related with only one field.  On the contrary, if there were no EM waves having only one field, let us make an EM wave having two component waves to pass through  a theoretical polarizer(i.e., by means of refraction), which do not permit orthogonal waves simultaneously, then only one component wave may pass through.  The one which crossed the polarizer, should contain only one type of field.  So, waves can be produced with only one field. This implies a contradiction to my earlier assumption.  I had this contradicting conclusion, because of my wrong assumption that there were no EM waves having only one field.   So, I have to conclude that there are EM waves having only one field.

But, I expect more.  No one can deduct simultaneously magnetic field part and electric field part from an EM wave.

Mr Moorthy

The statement "there is no EM wave having two component waves.  That  is EM waves have only one type of component waves" does not lead to "there are waves related with only one field".

There are EM waves with only one type of component wave.  They are electromagnetic waves with both magnetic and electric fields.  Maxwell's equations do not describe or allow waves with only electric fields or only magnetic fields.

Thanks Prof. M. White.  I like to wait for a while till I get one evidence(positively or negatively; mathematically or physically) from someone.

All Electrical energy, by definition has an E & H field existing together, at right angles to the direction of motion. This is a standard TEM wave otherwise known as the Poynting Vector ExH. When we observe what appears to be a charged up capacitor with a steady DC voltage we are in fact seeing the result of TEM waves traveling at the speed of light, for the medium, in opposite directions. A Capacitor can only support an Electric field at each so the TEM wave always reflects with the H field inverting to cancel out.

There can never be a single example of either H or E field, what appears as one or the other is defined by the boundary conditions. A S/C results in no E field, an O/C in no H field.   

(Apply a very fast digital step (50 pS) and watch how a Capacitor charges up. This shows the TEM wave bouncing back and forth along the Capacitor. (Parallel Plate TX Line).  Or insert a fast 50 pS pulse 2 nS wide and send it down a 75 ohm perfectly terminated coaxial cable. No reflections and this is a classic TEM step with both E & H fields.

Unqualified comment :

As of the question asked, there is no such thing to be confirmed/ identified in aided-tangible-visible sense, as E or H waves/field.

Prior knowledge both theoretical and its experimental evidence in measurable effect sense allowed us to restrict ourselves in understanding of this phenomenon (electricity sorts of ) as conventional E x M. It helps us because we made it up. That is actually sensible. We even designed our measurement scopes and other fancy stuff dictated by the phenomenon itself, somewhat.

In studying waves and wave fields , while manipulating quantities and dimensions, if forced to, one may at times (quite frequently, if close attention is paid) come across ratios and quantities and proportions connected by constants with the meanings of either speed of light or as times speed of light.

Again we somehow made it up and it is quite useful, it unambiguously resolves, reconciles and crystallizes lots of complicated phenomena which does not appear related, at certain levels.

.

To all contributors:

There is no molecule in the universe with diameter 10-6 meter. This statement is related to the question asked by me. A strong evidence in physics for the following theory is presented in an article attached, which provides a reason to the first statement. The theory is: An electromagnetic wave contains only an electric field wave or only a magnetic field wave. It is believed that researchers in mathematics have to do a lot for the question asked by me; although the question is related with physics.

Article Two Expressions for Electrostatic Forces and For Magnetic Fo...

To all contributors:

Experiments in astrophysics answered this question to some more extent. If the wavelength of an electromagnetic wave is less than 1.063 mm, then it is an electric field wave which is free from magnetic fields, and if the wavelength of electromagnetic wave is greater than 1.063 mm, then it is a magnetic field wave which free from electric fields. Details may be found in the article attached. We have yet to find suitable initial conditions for existence of these waves.

There is mention in one of the responses of the Poynting vector. This is the fundamental description of a TEM wave. ExH. E fields and H fields cannot be separated out. Space has two fundamental properties Mu and Epsilon, Permeability and Permittivity respectively. These defined speed c and Characteristic Impedance of the medium. There is no area of space where speed c of the EM signal is zero. Hence there is no such thing as a static Electric Field. A charged Capacitor still has ExH traveling at the speed of light for the medium. We only see E or a constant voltage because the H field in each direction cancels out. A changing H does not cause an E field and a changing E does not cause H. As one changes so does the other. Thus we can have a d(ExH)dt to represent a changing TEM wave. Maxwell got it wrong, there is no such thing as Displacement Current. An observed current with a changing applied voltage to a Capacitor indicated that the d(ExH)dt --> is not equal to d(ExH)dt

Dear Professor Malcolm Davidson

I again like to express that I accept Maxwell equations and wave equations derived from them. Problems appear in interpretation. I agree that both E and H may vary simultaneously. But they do not move simultaneously as moving waves. If H moves as a wave, then E does not move, but it varies in the place of generation. If E moves as a wave, the H does not move, but it varies in the place of generation. I shall prepare a very lengthy explanatory essay within few months to explain these things in detail.

I disagree with you. You cannot separate out the E & H fields from each other. A digital signal traveling down a twisted pair for example is a defined ExH signal. Oliver Heaviside called it Energy Current. As I mentioned space supports a signal traveling at speed c for the medium. I am interested to read your description of a static field, which would break the basic laws of nature.

To Prof. Malcolm Davidson

I agree with you sir for one reason. The fields E&H are not separated at a place of production of EM waves, and they oscillate simultaneously. But, when the fields are propagated as energy waves from the place of production, only one field emerges as EM waves. I like to say some more words. In my articles I define EM waves as energy waves having the speed c in vacuum, and I do not consider the other mediums. This specification avoids alpha rays, beta rays, and microwaves from discussions. This is given for clarity, because the readers should not consider their EM waves. As I said I shall prepare my explanation with many figures, and I shall try to make the approximate length number 1.063 mm as an important number.

I think that such a simple evidence does exist. Let us consider a radio receiver. You need an aerial to receive the signal. The aerial can be either a wire like stick and you receive the electrical component of EM wave, or the aerial can be a coil with the ferrite core inside and you receive the magnetic component of EM wave. You can also prove the position of the stick earial and the ferrite one at which the sound volume is the best. These positions are perpendicular each other. Usually the stick aerial is vertical and the ferrite one is horizontal.

To Prof. Libor Gajdosik

If there are two perpendicular sticks, then it may give a conclusion that there could be two perpendicular components in an em wave. If one is a stick and another one is a coil then there is a chance to consider coil as circles parallel to the other stick, and in this case the previous conclusion may not derived. So, I have to understand the functions of the components of the types of aerials mentioned by you. I shall try to do the same. I thank you for your answer.