PAGE TWO OF: What Is "Electricity"?

(c)1996 William J. Beaty
Electrical Engineer


What is electric charge?

Electric charge, also called "the Quantity of Electricity," is a funamental component of everyday matter. Objects are made of molecules and atoms, atoms are made of protons, neutrons, and electrons, and the protons and electrons are made in part out of electric charge. Electric charge is substance-like. If you have a quantity of charge, you cannot destroy it, you can only move it from place to place. A flow of electric charge is called "electric current."

Here's an interesting problem. Electric charge once had a different name. It was called "electricity" by nearly all scientists throughout history. They said things like "charge of negative electricity" or "charge of positive electricity." They called electric currents by the name "flows of electricity." Eventually they changed the name and stopped using the word "electricity." They called it "electric charge" or simply "charge." Yet the old Quantity of Electricity definition is still used by Britannica, and the CRC Handbook, and the SI units definitions of NIST.

See also:
What is electric charge?

Scientists' definition of the word "electricity."?

Misconceptions about charge

What is electricity, REALLY? ("charge" versus energy)

What is electrical energy?

Each of these is a kind of electrical energy:
  1. X-rays
  2. Light
  3. Microwaves
  4. Radio signals
  5. Telephone signals
These five things really are exactly the same, only their frequency is different. We can add two more items to the list above. Power lines carry the same "stuff" as above, but the frequency is even lower, it is 60 cycles per second (50Hz in Europe.) And batteries produce the same "stuff", but the frequency in that case is near zero. Lets add them to the list:
  • X-rays
  • Light
  • Microwaves
  • Radio signals
  • Telephone signals
  • 60Hz energy from Electric company generators
  • DC energy from batteries

Electrical energy is also called "electromagnetic energy" or "EM energy" or "electromagnetic vibrations." Electrical energy is a type of wave energy, and these energy-waves always move very quickly (they usually move at the speed of light.) When you turn on a wall switch, the light bulbs light up instantly because the electrical energy moves so fast.

Electrical energy is a combination of two things: magnetic fields and electrostatic fields. Electrical energy can be guided by wires, but also it can travel through space without any wires. For example, if we wave a bar magnet near a coil of wire, electrical energy produced by the moving magnet will leap into the coil even though the magnet did not touch the coil. Another example: if we build an antenna that's about 5000 miles long, we can plug it into an AC wall outlet, and the electrical energy will be broadcast into space and lost. There is no basic difference between "radio signals" and "AC Power", only their frequency is different.

Also see:

What is electrical energy?
What is electricity, REALLY?
Electricity is not a form of energy

What are electrons?

Everyday matter is composed of atoms, right? But atoms are composed of protons, neutrons, and electrons. This tells us that atoms are patterns, and that that everyday matter is just a big bunch of protons, neutrons, and electrons. Electrons are a natural part of everyday matter. MATTER IS FULL OF ELECTRONS. This is important, because whenever an electric current appears in a copper wire, the electrons already present within the copper are forced to flow. As far as wires are concerned, "electric current" means "copper's electrons start flowing."

Here's the most important part: batteries and generators don't put those electrons into the wires. The electrons were already there, because wires are made partly of electrons. When you plug a lamp into an AC outlet, the electrons already inside the copper wires are forced to vibrate back and forth.

An analogy: if sound is like electrical energy, then air molecules are like electrons. How do sound waves travel? They are travelling vibrations in the air. How does electrical energy travel? It is a vibration that travels in the "cloud of electrons" inside of metals.

What is electric current?

Whenever electric charge moves or flows, that is an electric current. The words "electric current" are the same as the words "charge flow."

An Analogy: If charge is like air, then electric current is like wind. Or if charge is like water, then Electric Current is like "gallons per second" of water flow.


What is an imbalance of charge?

Objects are matter, and among other things, matter is made from a combination of positive and negative electric charge. When the quantities of positive and negative charge aren't perfectly equal, there is an imbalance of charge. An imbalance of charge is commonly called "static electricity", but this can be misleading because there is nothing really "static" about it. If a charge imbalance should flow along... it's still an imbalance; it's still "static electricity."

See also:

Red and Green Electricity
"static electric" misconceptions

What is an electric field?

When positive charges attract negative charges, there is an electric field joining the charges together. Electric fields are a lot like magnetism. Both are invisible, both contain "lines of force," and both can reach across empty space and cause things to attract or repel. However, electric fields are NOT MAGNETIC. They are a whole different thing than magnetism. The poles of a magnet are surrounded by a magnetic field, but how do we create an electric field? Just rub a balloon on your hair! Charged objects create electric fields in much the same way that magnet poles create magnetic fields. So what is an electric field? One answer: north and south magnetic poles create magnetic fields, while positive and negative ELECTRIC POLES create electric fields.


What is voltage?

"Voltage" or "electric potential" is one way that we can measure an electric field. To produce a very high voltage, rub a balloon on your head, or scuff your shoes upon the floor when the humidity is very low.

Electric fields can push or pull upon electric charges, so electric forces are caused by voltage (or instead we could say that voltage and electric forces are caused by electric fields.) In a battery circuit, the voltage from the battery causes the charges of the wire to flow. VOLTAGE CAUSES CURRENT. Some people like to say that voltage is a sort of "electric pressure." That's almost correct (it's correct as far as grade school is concerned, but in physics classes we will learn that voltage is not pressure, not exactly.)

Another answer here.

What is electric power?

"Electric power" means "flow rate of electrical energy." If electrical energy was like water, then electric power would be the gallons-per-second. Energy is measured in Joules, and when energy flows, the flow is measured in Joules per second. What is a watt? The word "Watt" is just another way of saying "Joule per Second." Energy comes in Joules, while power comes in Joules per second.

The important part: while energy is very much like a stuff, power is not. Power is a FLOW RATE of energy, or a RATE OF USE of energy. We can store electrical energy, but electric power is not something that is ever stored. (Think in this way: we can store gallons of water, but it's impossible to store any "gallons per second" of water.)

Also see:

How are Watts and Amps different?
How are Watts, Amperes, and Volts related

What is a spark?

An electric spark is a volume of air which has been electrically converted from a gas into a plasma, the fourth state of matter. While plasma can be created by high temperatures, it can also be created electrically when a high voltage pulls loose the outer electrons of air molecules.

Sparks are made of glowing air, and the color of the spark depends on the type of gases involved. Sparks in nitrogen/oxygen are bluish-violet, while sparks in Neon are red/orange. (Yes, the glow inside a neon sign is a kind of fuzzy low-pressure spark.)

Also, sparks are conductive. Once formed, they can contain an electric current in much the same way that a wire can. In many ways a spark is like a bit of air which has been turned into an electrical wire. When you watch a thunderstorm, imagine that the clouds are throwing out highly charged wires which will explode if they touch the ground. Or when watching a Tesla Coil, don't forget that the glowing fractal streamers are conductors with alternating current inside.

Sparks can leap in either direction regardless of polarity, and can leap from both a DC electrode or an AC electrode. They can start on a DC negative electrode and jump towards positive. Or they can start on the positive and go towards the neg. They can even start in the air between two electrodes and spread outwards in both directions.

Sparks in air involve avalanches of electrons from the air molecules, but they also involve photons of Ultraviolet light. The strong electrostatic field at the tip of a spark causes nearby air molecules to break apart into separate electrons and ion as a free electron strikes molecules and releases more electrons in an avalanche. Air turns into plasma. But also the electrons captured by atoms can give off ultraviolet photons, and if this light is absorbed by nearby air molecules, it can knock electrons off and spread the plasma that way. (And if gamma rays or Beta particles from background radioactivity should strike a growing spark, they can grow it much faster as a gamma/Beta spark rather than a UV/electron spark, by the process of Runaway Breakdown.)

Another answer here.

What is electromagnetism?

"Electromagnetism" usually means "electrical energy" or "electromagnetic fields."

Another answer here.

What is electrical science?

Electrical science is the study of electrical effects... and electrical effects are caused by electric charges and by the electric and magnetic fields associated with charges. Electrical science is divided into sections called Electrodynamics, Electrostatics, Magnetism, and EM wave mechanics.

Electrical science is often called "electricity," which can be confusing. For example, the study of lightning is the study of electrical science, so the study of lightning is the study of "electricity." But this doesn't mean that lightning is "made" of electricity. When we study lightning, we are studying a science topic, and we're not studying a substance called "electricity."

It might be better if electrical science had some other name than "electricity." After all, the study of light is not called light. It's called optics. Nobody thinks that lenses and light bulbs are made out of light, since whenever we study lenses and light bulbs, we study "optics." Optics is obviously a science topic. But plenty of people think that lightning is made out of electricity, since whenever we study lightning, we study a science topic named Electricity, and most people imagine that we're studying a SUBSTANCE named "electricity." which looks like blue-white fire that reaches across the sky.

"Electricity" or Electrical Science is confusing in another way. This science topic is divided into two sections called Electrostatics (the study of charge and voltage), and Electrodynamics (the study of current and changing fields.) Many people have convinced themselves that there are two kinds of electrical energy: static and current. Wrong. In truth, there are two kinds of ELECTRICAL SCIENCE: Electrostatics and electrodynam ics. Since "electrical science" is called "electricity," we can say that the two types of electricity are static and current. What we MEAN is that the two types of electrical science are the study of charge and the study of charge-flow. See what's happening here? A field of science has been mistaken for a type of energy! And the two fields of science, Statics and Dynamics, have been mistaken for two separate KINDS of energy.

How many K-6 textbooks insist that "static electricity" and "current electricity" are the two main forms of energy? This is a weird distortion which probably arose over many years of misunderstanding. What they MEAN is that there are two types of electrical science, one dealing with charge and voltage, and the other dealing with currents and circuits. Two kinds of "electricity," where the word "electricity" means Electrical Science.

What is electrodynamics?

Electrodynamics is a field of science and a class of phenomena which involves electric current, magnetic fields, and attractive/repulsive magnetic forces. The study of generators, motors, circuitry, electric currents, etc., falls under the heading of "electrodynamics."

What is electrostatics?

Electrostatics is a field of science and a class of phenomena which involves charged subatomic particles, net electrical charge, electric voltage, electric fields, and attractive/repulsive electric forces.

What are electrical phenomena?

"Electrical phenomenon" means "electrical happening." When you turn on a flashlight, that is an electrical phenomenon. During a thunderstorm, the thunder is an electrical phenomenon and the flashes of light are electrical phenomena.

Unfortunately the term "electricity" means "electrical phenomenon." This causes confusion, because sparks, wires, batteries, currents, and voltage are all electrical phenomena, so they are forms of electricity. See what I just said? Batteries ARE ELECTRICITY. Sparks ARE ELECTRICITY. Electron flows ARE ELECTRICITY.

But these are not such odd statements. After all, transistors and radios and computers are electronics. When we hear about "electronics", we don't end up thinking that "electronics" is some kind of weird invisible energy that's hidden inside our computer. The word "electronics" fortunately has a clear meaning.

Not so with "electrical phenomena" or "electricity." If someone tells you that motors are electricity, you'll probably get the right idea (motors are electricity just as transistors are electronics.) But if someone tells you that lightning is electricity, or that electric currents are electricity, you probably WON'T decide that lightning and currents fall under the heading of electrical phenomena. Instead, you'll probably decide that currents and lighting are MADE OUT OF "electricity," and that "electricity" is a very strange substance indeed.

Created and maintained by Bill Beaty. Mail me at: .