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WHAT IS "ELECTRIC CHARGE?"What is electric charge? Well, there's an easy answer and a hard answer. Here is the easy answer:
Charge is...
THE LESS-EASY ANSWERIf we look up "electric charge" in a dictionary, we encounter a problem. The definition of "charge" is circular. What is charge? It's the stuff that causes electrical phenomena. What are electrical phenomena? Those are the things caused by charge! Simple, no?(grin!)
There is a good reason why the definition of "charge" is circular. Like
mass, length, and time, Electric Charge is a "fundamental." Many
dictionaries say this: "Electric charge: a fundamental property of
matter." The word "Charge" is used to define other things, and
therefore the definition of the word "charge" becomes a serious problem!
What is an electric current? It is a flow of charge. What is electric
charge? It is the stuff that flows during an electric current! The
circular definition is hard
to avoid because normal definitions are
based upon deeper concepts, and when we finally arrive at the deepest
concepts of all, we cannot "take them apart" into their fundamental
pieces. What is charge? What is mass? What is time? This is like
asking "what is 'WHAT'?" or "what is 'IS'?" Very hard to answer. Yet
there is a way to do it: look at the context in which we use the word. In
other words we can work backwards and define Charge in terms of
more complicated concepts. Yes, the definitions still will be circular.
However, the definitions point at each other in a certain special pattern.
We can understand "charge" by becoming familiar with this pattern.
To find the special pattern, go look at the list at the top of this page.
THAT'S where the words "electric charge" are explained.
Electric charge is a component of atoms. In other words, after we have
broken an object into molecules, and broken the molecules into atoms, when
we break the atoms apart we discover particles of electric charge. Charge
is material, it is like atoms but it is one step lower than atoms. Most
science textbooks tell us that solid objects are made of atoms. It is
also valid to state that solid objects are made of electric charge.
Objects are made of equal quantities of positive and negative charge, and
objects stay together because of the attraction between the quantities of
opposite charge inside them. Chemical bonds are electrical in
nature.
Charge flowWhen charge moves, what do we call it? Well, if the positive and negative charges move along together, we call it "physical motion." Since matter is composed of charge-carrying particles, all physical motion is a motion of charge, but in most cases both the negative and the positive charges move along as one. When opposite charges move separately, THAT is when interesting things occur. Opposite charges moving along together are "mechanical", while opposite charges moving differently are "electrical." If the negative charge in an object should start moving while the object's positive charge stays at rest, then we call that motion an electric current. The words "electric current" mean the same as "charge flow."
Charge: it's not energyCharge is not energy. A quantity of charge can have many different amounts of energy, and if you know the amount of charge, you have no knowledge of the amount of energy present. Charge and energy move differently: in AC cables the charges sit in one spot and slowly wiggle, while the energy flows along at almost the speed of light. (Charge is as different from electrical energy as air is different from sound waves!) Charge in circuits flows slowly in a circle like a drive belt, while energy moves quickly from the source to the load. Some people think that since charge and electrical energy are mysterious and invisible, they must be the same thing. But see below: electrical energy is invisible, but charge is definitely VISIBLE. And finally, J. C. Maxwell points out that charge and energy MUST be two different things, since the energy is found by multiplying the amount of charge by the voltage of that charge.
Charge is "poles"When the positive and negative charges of matter are sorted out and pulled away from each other, "static electricity" is the result. When (+) is pulled away from (-), an invisible force field connects them and causes them to attract each other. This field is similar to magnetism in many ways, but it is not magnetism, it is called an Electrostatic Field, or "e-field." With magnetism, the lines of force spring from the north and south poles of magnets, and these lines seem to connect the opposite magnetic poles together. In Electrostatics, the electrical lines of force connect the (+) and (-) poles together. What is charge? It is the "pole" where the electrical lines of force come to an end. Follow the lines of a static "e-field" along, and eventually you'll arrive at a small bit of "charge." Electric charge is the glue which attaches the flux lines of e-field to the particles of matter.
Charge: it's not invisibleCharge is not invisible. Whenever light bounces off an object, it bounces off the outside of the atom, and the outside of an atom is made of negative charges. In other words, electric charge reflects light. Yet when we rub a balloon on our hair, the balloon (and the hair) don't look different. How can charge be visible if we see no visible difference when we electrify a balloon? Simple: the balloon's excess charge is way too small. The imbalanced charge caused by rubbing a balloon on your head is like a teacup poured into the ocean: it is very tiny when compared to the charge which is already there. The balloon is made of charge, and the amount of charge that is added or removed by the hair is incredibly small. If we could add a billion times more charge to that "charged up" balloon, then we would see some changes in its color. But the poor balloon would instantly explode violently outwards because alike charges on its surface would fiercely repel each other. (Here's a clue: when a significant portion of the positive charges in a block of Uranium become disconnected and fly away from each other, that's called a nuclear explosion.)
Here is a way to see charge directly: look at the surface of a wire.
Metals look metallic because they contain a "fluid" composed of movable
electrons. This electrical "fluid" is an excellent reflector of light
waves, and it causes the surfaces of metals to act like mirrors. It's
these same electrons which flow during an electric current. The "silvery"
stuff of a metal is the charge. What is charge? It is a "silver
liquid" which is found in all metals, and which can be forced to flow.
Even though the charge is visible, its flow is not. Look carefully at
wires in an operating electric circuit and you won't see anything moving
along. This is not very mysterious: stir a glass of water and then look
for the flowing motion. You'll see moving bubbles and perhaps moving
specks of dirt, but you won't see the water move. The silvery
charge-fluid in a wire has no bubbles or dirt, so even though the charge
is visible, we cannot tell if it is moving or still.
Do you still need a definition of "Electric Charge?" I can do no better than the dictionaries: Electric charge is a fundamental property of matter which is the cause of all electrical phenomena. Electric current is a flow of "charge," and when opposite charges are separated, "static electricity" (electrostatic phenomena) appears.
Other Articles:MISCONCEPTIONS ABOUT CHARGE
RED AND GREEN ELECTRIC CHARGE DEMONSTRATION
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