Veritasium: No Power in Power Lines
Michael James Scharen

michaelsbookcorner.com
December 1, 2021

Concepts we learned in school or elsewhere are often incomplete. Did we ever really understand them?.

Electric shocks come in many ways. The latest comes from Veritasium in a video entitled The Big Misconception About Electricity. The conjecture, in this production of less than fifteen minutes, has caused a significant ruckus among everyone from part-time tinkerers to university professors. This author, with a B.S/M.A. in Physics, must confess that he and many of us have suffered in intellectual darkness for a long time!

What Do You Really know and When Did You Really Know it?

The crux of the video is that most people, including many physicists and electrical engineers, have not fully grasped a concept derived in the 19th century. Namely that electrical power does not flow in wires and is not carried by electrons. Power flows from the surrounding fields generated by and and associated with the electrons. This requires a bit of explanation, so please be patient if the concepts are new. Pay attention in class if they are not. We must beware. The crux of the article is that we must avoid traps created by previous simplistic explanations of reality - even those offered by learned professors.

Historical Note

Michael Faraday discovered the magnetic fields associated with moving charges -  also in the 19th century. Simply stated, and this is dangerous, the magnetic field lines form in a circle about the direction of motion for a moving charge, as with a current of electrons in a wire. Faraday observed the motion of compass needles near a wire as he discharged a battery thus supplying it with current. The Scottish genius, James Clerk Maxwell - in four equations - mathematically described the full complimentary phenomenon whereby changing electric fields bring about magnetic fields in complimentary fashion. Changing magnetic fields will induce electric fields and currents in good conductors. And then there was light - which follows the same formulas.


Fig. 1 Beams or photons of light or any electromagnetic wave is made up of perpendicular oscillating electric and magnetic fields. A changing electric field creates a changing magnetic field and vice versa. Light or energy, moves ahead with the Poynting vector, after John Henry Poynting  --  perpendicular to both E and B.

Innovations were made culminating in Nicola Tesla's invention and perfection of electrical generators and ac motors utilizing electromagnets made from the winding of wires. And on top of that - radio. (Sorry, Marconi, but you used Tesla's patents and stole the credit!) This has given us the world in which we live today. Without the ability to turn mechanical energy into electrical, and vice versa we would all be whistling in the dark.

Back to the subject at hand -- the origins of what we call electrical power - the Veritasium video reminded everyone that power follows the Poynting vector, not the current. The Poynting vector, denoted as S is the result of a type of multiplication called the cross-product derived from the magnetic field which physicists denote as B and the electric field, E. All of these are vector quantities. A vector is a value which has a magnitude and direction. Just as a debt or credit has an amount -  value is positive or negative - the vector result of a cross-product has an associated sign which denotes direction. The method for determining this direction follows the Right-Hand-Rule.

Just a Few Tools


Fig. 2 The Right-Hand-Rule for vector cross-products is shown for the cross product of a x b resulting in the mutually perpendicular vector c. The magnitude of c is proportional to |a| x |b|. For vector cross-products, multiplication order determines the resulting direction. a x b points in the opposite direction of b x a.

Derived from the cross-product of E and B, the Poynting vector, S denotes the direction for the flow of energy. By the right hand rule, this energy always flows perpendicular to both the changing E and B fields. What the Veritasium video shows with such mind-blowing clarity is that power flows into a resistor, light bulb, or toaster from a completely unexpected direction -- from the surrounding space.


Fig. 3 In this diagram, there is a battery connected simply in a DC circuit with a resistor as the load. Magnetic field is denoted as H, green electric field as E, red, with the Poynting vector, S, blue.

Variations of this diagram appear in many of our old dusty textbooks on Electricity and Magnetism, yet how many of us harried as students absorbed it? How many professors took the time to discuss the implications (if they, themselves understood them)? To be fair, many of us, including this author may have had a feel for this even if we could not explain it. A situation from personal experience will be related below.

The Meat

In the diagram above, we have a simple DC circuit. We know that energy leaves the battery and equivalent energy is spent as heat and/or light in the wires and resistor, light bulb or toaster. But how many had this picture in their minds? Many of the unenlightened just took it for granted that it was electrons moving through the resistor and bashing into other atoms or electrons which dissipated their energy. One of my own professors described it as being in a jeep in an orchard, heading for lunch with the trees (atoms) jumping out of position and stopping the vehicle! The truth is that the electrons do flow, but not swiftly enough for that kind of energy expenditure. In an AC circuit, they simply jostle back and forth in place.

Follow the blue Poynting vectors in Figure 3. They all flow out perpendicular to the battery and wire on the left side. They follow both the positive and negative wires toward the resistor. At the resistor, the Poynting vectors, and energy flow, are directed back into the resistor from the surrounding space in opposite fashion to that for the battery! The energy seems to mysteriously leave the battery for the ether, then return from the ether to the resistor!

We must note here that DC or AC does not matter. Let us remember our old friend the cross-product. For alternating current, both B and E fields switch direction. In multiplication, even for cross-products, positive x positive is positive and negative x negative is also positive. The end result is the same direction for the Poynting vector, and energy flow - toward the load. It is rather like those jostling electrons are the engine of a conveyor belt of energy.

Electrical engineers do not follow the conventions in this manner always, but they do have an instinctive feel for it. There is a reason why high voltage power lines are strung so high up in the air. The utilities wish to maintain the field between the wires and keep them isolated from the ground as much as possible. The Earth is lossy or resistive, thus wastefully dissipating power away from paying customers and into the ground.

A Practical Case from Experience

As promised, or threatened above, this author encountered a related problem in the development of microstrip elements for use as passive microwave filters and other devices. For such elements, good grounding is very important. In the microstrip configuration, the center conductor is patterned on one side of a planer substrate over a conducting ground plane on the opposite side. This is akin to taking a coaxial cable and folding it open so that the center wire has nothing above it but air and dielectric below with the outer sheath of the coax remaining as ground.


Fig. 4 RF microstrip configuration. The top strip is the 'signal line' while the plane below is ground. Fields concentrate between signal and the ground plane. HTSC circuits consisted of MgO substrate as dielectric with HTSC as both signal and ground layers. Gold was deposited on both sides to provide ohmic contacts.

We were still evaluating our materials while proceeding with circuit design and measuring the RF performance. One tool was a microstrip 5 GHz resonator which is basically just an isolated strip running across a square substrate with capacitor coupling gap on each end. Energy resonates at 5 GHz rather like sound resonates when we blow across the top of a bottle. Only certain frequencies and harmonics will fit. In an attempt to improve the grounding which was tricky with the ceramic material, ohmic gold was deposited on the superconductor ground plane. The author developed and refined this process for Superconductor Technologies Inc.. At any rate, the Q, or sharpness of the resonators, or measure of their performance became severely degraded after the addition of gold to the ground plane.

While reading many papers on ceramic superconductors, the author came across measurements for the magnetic penetration depth for these materials. Basically, this was a measure of how far into the material the magnetic field would go as it was exponentially attenuated. It was pointed out to the leading engineer that this depth was 3–4 times the thickness of the superconducting ground plane and that the magnetic field was now into the gold underneath. He ordered more resonators -- this time with just a gold border left on the ground plane to mate with the test package -- far away from the signal line. It worked! The Q went back up as there was no longer normal metal close by where eddy currents and losses would detract from performance.

What Does It All Mean?

The seen and the unseen in physics is far more fascinating than many realize. The Poynting vector and power flow need not be looked at in all of the equally, yet intensely complex and interesting mathematics, but by just looking at those high tension lines or your toaster next time in a slightly different way. Be like Einstein and picture things you could never see. Do that thought experiment by imagining how that power really flows all around us -- directed by mere mortals.

The late, great physicist, Dr. Richard Feynman was quite blown away by this concept! Richard Feynman was a Nobel winning physicist who worked on the Manhattan Project during WWII. His Feynman Lectures on Physics (which I never had time to absorb) are renowned as the bongo playing professor could make the most intense subjects understandable to laymen and new students. Incidentally, he was the greatest among eggheads called by NASA to analyze the first space shuttle disaster. He cut through the b.s., took an O-ring he suspected and tested it in ice-water himself. Sure enough, that was what cracked - causing the explosion. It was the failure of the O-ring in cold weather. We need a whole army of Feynman's now.

Michael James Scharen is a science-fiction author and former researcher in High Temperature superconductors and product development. Other roles included test and manufacturing. His website is michaelsbookcorner.com.

For reference, please check out Veritasium and their stir raising video THE BIG MISCONCEPTION ABOUT ELECTRICITY