What in the world is electricity? What’s the difference between “energy” and “power”? These things are real, but immaterial. They have no weight and don’t seem to be made of “stuff,” as other things always do.
When anything in the universe changes, “energy” is always absorbed or released. The universe’s total amount of energy is constant. For example, changing a log into ashes releases energy; changing raw ore and rusty scrap into shiny new steel absorbs a lot of heat energy.
“Power” is what you need to make changes fast. For example, a powerful car can change its speed more rapidly than an underpowered one.
Opposites attract. There are two kinds of electric “charge”: “electrons” are those lively subatomic particles whose home is usually the outer “atmosphere” of atoms. “Protons,” their oppositely-charged counterparts, are much heavier and usually reside deep inside the core or nucleus of atoms.
Protons can’t move in wires, but electrons can. Protons remain trapped together in their nucleus for a very long time, except in acids, which are typically full of free-swimming protons.
The electrical attraction between protons and electrons is one of the strongest forces in the universe. It accounts for the great strength of a piece of steel, and it holds together the rugged proteins in your own skin, muscles, and bones. It provides the “oomph” that moves electricity in batteries, and we measure that amount of “oomph” in volts.
Voltage describes the amount of energy each electron is able to carry. Super-strong proton-electron attraction is the “magic” inside the lead-acid battery in your car. When you
crank the starter, protons in the battery acid begin snatching electrons from the oxide-coated lead plates attached to the positive side of your car’s 12-volt battery.
Whenever a switch is “on,” a path between the positive and negative posts of your battery is available through the car’s wiring. Replacements for the snatched electrons stream to the positive post through wires, making the starter motor move as they pass through it.
When you halt the march of electrons by turning the starter switch off, the protons are forced to stop as well, since additional electrons are suddenly unavailable. Your battery can remain in this
halted state for weeks or months, “charged up” and ready for the next time you want to start the car.
You can imagine electricity in wires as if electrons were flowing like water through pipes. The amount of electrons flowing (the “current”) is measured in “amps” and is analogous to gallons per minute delivered by a pipe.
Contrary to popular belief, electrons don’t zip along a wire at the speed of light. Instead, an
unimaginably vast number of them move fairly slowly, taking many seconds to move an inch. (More voltage makes them move a little faster.)
Although it is true that electric signals travel at the speed of light, the electrons themselves don’t move very fast. Just as the tug on a chain is felt instantly at the far end, it is not necessary for a single link to travel the entire length of the chain to deliver the tug.
When a switch closes, electrons begin to move, and an amazing thing happens. The instant an electric current starts flowing in a wire, a powerful magnetic pulse radiates outward, streaking out in all directions across the universe at the speed of light! And when the switch is turned off, that magnetic field collapses back into the wire at the same extreme speed, returning all its energy back to the circuit.
The opposite also happens; a magnetic field zooming past a wire induces all the electrons in it to move along to make a new current. (A motionless magnet has no effect, however.) This extraordinary electromagnetic phenomenon not only makes wireless communication possible, but on an industrial scale, powerful magnets and thousands of coiled wires generate electricity for the grid.
How is the electricity you buy made? The “moving magnet” trick is how nearly every power plant generates electricity. Whether the magnets are put in motion by fuel-burning engines, nuclear-heated steam turbines, hydro, or wind power makes little difference. The electrical result is identical.
Because the rapidly spinning magnet shows the wire its North pole, then South and North again, the direction of the current in the wire reverses direction each time. This is why house current is called “Alternating Current” or AC.
In North America, home electricity alternates direction 60 times every second, but the electrons only move a tiny distance before they turn back. So, the electric company can’t be billing you for the total number of electrons they delivered each month. That always averages out to zero!
Generators are mechanically identical to electric motors. Turn the shaft, and electricity flows out of it. Or supply electricity to it, and its shaft will begin to turn. This is the secret to “regenerative braking” in electric vehicles — motor/generators return energy to the batteries while also stopping the car.
There is one way to generate electricity that stands apart because no moving magnetic field is needed — solar power. Light energy striking the dark “photovoltaic” material knocks electrons out of its atoms, and those electrons are collected by thin metal wires on the surface, run through wires to your house (or possibly a neighbor’s over the grid) before returning to drop some replacement electrons back on the dark side of the panel.
How does the power company figure out how much to bill you? More than a century ago a meter was invented that is nothing more than a little motor running a clockwork, driven by the current in the wires entering your house. The meter’s revolutions record the voltage and current going into your household over time, essentially multiplying the number of volts, amps, and hours together.
The company bills you for the resulting “kiloWatt-hours.” When you turn something on in your house, the meter’s “motor” begins to run. When you turn more things on, it runs faster. If you have solar panels, it could run backward!