Directional wires/cables

For those who find it hard or impossible to visualise how a signal can travel faster than the stuff it travels through, consider how sound reaches your ears from a loud speaker.

Air comprises molecules randomly whizzing about in all directions, and sometimes colliding with each other and the surroundings. When the speaker cone moves forward, some of the nearby molecules get a slight extra shove in the forward direction.  They pass this extra shove to the molecules near them, and so on.. The extra shove reaches your ears at the speed of sound, but no molecule has to directly travel from the loudspeaker to your ear, let alone at the speed of sound  There is no need for a sonic jetstream, 

This is similar to the behaviour of the cloud of free electrons whizzing about in a metal, responding to a voltage signal.

Or think of a long train (our record in Australia is 4.5 miles long with 682 cars and 8 locomotives), The couplers between the cars are designed to have a small amount of slack so overall the train stretches when pulled and compresses when braked.  Imagine the train is stopped.  Apply power to the lead locomotive, and the coupling to the next car will stretch a bit before that car starts to move.  The process ripples down the length of the train.  After a short while, the signal that the train is moving arrives at the last car (a mile or more from the loco) though overall not one of the cars has moved more than a few yardsl.

@jea48 

I learned in 2010 what I was taught in K thru12 was wrong how electricity works.... Four years of electrical apprenticeship training I was taught the same wrong crap

Nevertheless, it would be helpful if you could remember how to apply Ohm's Law, and how power is calculated in electrical circuits!  Fortunately, when wiring houses, you don't need to work things out from first principles, because engineers have done this for you and experts have written building codes to follow.

My partner's son leads a crew working on high voltage transmission lines running hundreds of thousands of Volts, but in Australia he is not officially qualified to install a 240-Volt outlet in his own home!  That would be against government regulations.

Talking of government, a while ago I sold an upgrade to The Canberra Hospital's digital imaging system, which was the source of all patient records.  I included a big uninterruptible power supply (UPS) with rectifiers, batteries and inverters.  The hospital insisted that their own electricians do the installation.  When I inspected the finished system, there was a computer room with hospital grade power outlets, red for the high-availability outlets, beautifully run back through a distribution system to the UPS.  But the UPS only had one cable connected - the output.  The electricians (we call them sparkies in Australia) had "forgotten" to run mains power to the UPS.

@jea48 

I see you didn't bad mouth Ralph Morrison. 

Ralph Morrison What is Electronics

"If we accept the idea that fields carry energy in space, it must be true at all frequencies. That is the law. If it is true for light, it must also be true for 60Hz power and at DC. For utility power, the energy travels in the space between conductors, not in the conductors. This is not the picture presented by circuit diagrams, where energy seems to be carried by conductors. In digital circuits, the signals and energy travel in the spaces between traces or between traces and conducting surfaces.

Buildings have halls and walls. People move in the halls, not the walls. Circuits have traces and spaces. Signals and energy move in the spaces, not in the traces."

No, I could not be bothered but I will have a little crack at him now!

If it is true for light, it must also be true for 60Hz power and at DC.

Light is an example of electromagnetic radiation which can be visualised in classical physics as synchronised oscillations of electric and perpendicular magnetic fields.  In a vacuum, they travel at the speed of light.

They are reinterpreted in quantum physics as streams of photons, which are uncharged particles with zero mass when they are at rest.  Photons do not obey the Pauli exclusion principle.

In this context, 60-Hz power and DC surely refer to electricity?  60-Hz electromagnetic waves are very low frequency radio waves!  DC is not any sort of wave.

Electricity is the result of charge, and charges are carried by electrons and other particles which do obey the Pauli exclusion principle.  Similar charges strongly repel, and opposite charges strongly attract.  Richard Feynman has stated that every electron affects every other electron in our universe.

Electric currents are not a form of Electromagnetic radiation - Wikipedia.  Mr Morrison is confusing photonics and electronics (electricity in particular).  Having got that fundamentally wrong, his assertion that electrical energy is carried in the spaces between conductors is equally wrong.

His speciality seems to be circuit board layout for digital circuits.  His message is to beware of interference between adjacent traces, especially in multi-layered applications.  This is good advice, not because of electromagnetic radiation, but because every electron interacts with every other electron.  (Photons are much better behaved!).

In digital circuits, the signals and energy travel in the spaces between traces or between traces and conducting surfaces

Surely traces are conducting surfaces?

The circuit board traces are the conductive halls filled with crowds of free electrons.

Finally, digital circuits typically operate at or near Gigahertz switching rates.  The skin effect is very important at these rates.  Almost always the switching is done in integrated circuits based on doped semi-conductors, not conducting metals.  The quantum properties of the electron turn this subject from electrics into electronics, often at the nano-scale.

If Mr Morrison believes in his "law" he should change his title to "What is photonics"