Up to SCIENCE HOBBYIST | Up to MISCONCEPTIONS
"ELECTRICITY" MISCONCEPTIONS IN K-6 TEXTBOOKS - - -William J. Beaty
"ELECTRICITY" IS A PHENOMENON COMPOSED OF ENERGY? Wrong.
Actually, "Electricity" does not exist.
The term "electricity" is a catch-all word with many meanings.
Unfortunately these meanings are contradictory, and this leads to the
unsettling fact that there is no single substance or energy called
"electricity." When we say "quantity of electricity," we could be talking
about quantities of charged particles. But we could also be talking about
quantity of energy, quantity of current, or potential, forces, fields, net
charge, power, or even about electrical phenomena. All of these are found
as separate dictionary definitions of the word "electricity." But current
is not power, particles are not fields, and charge is not energy.
"Quantity of Electricity" is a meaningless concept because of the
contradictory definitions of the word "electricity."
Much of this problem would vanish if we used the word "electricity" only
to refer to a field of science or class of phenomena. This is the way we
use the words "physics" or "optics." Then, if we needed to get down to
details, we would never say "electricity." Instead we would use words
like "charges," "energy", "current," etc. We do use the word
"electricity" this way occasionally. But then we immediately turn around
and do the equivalent of teaching our children that optics is a substance,
or that physics is a kind of energy. "Optics" is a substance which comes
out of the light bulb and passes through the lens, right? And when you
ride a bicycle, "physics" comes out of your muscles and makes the wheels
Below are a few examples of errors caused by the contradictory meanings.
- In AC electric circuits the *charges* wiggle back and forth,
but the *energy* moves continuously forward. This is analogous to the way
that sound waves move continuously forward through the air, while the air
itself wiggles back and forth. But if we teach our kids that "electricity"
is made of electrons, and "electricity" is also energy, then we make a
serious error. We unwittingly teach that electricity in wires sits in one
spot and wiggles, but at the same time the electricity moves forward rapidly.
Garbage! It's like saying that sound and air are the same thing. And the
error is directly traceable to the bogus "electricity" concept.
Another: when a battery lights a lightbulb, we explain that the path of
electricity is into, then through, then back out of the bulb, and that
no electricity is
used up. Then we say that electricity flows from the battery to bulb and
is totally converted to light. Which one is correct? Does the bulb consume
the electricity? Or, does all the electricity flow through the lightbulb
and back out again? As far as students are concerned, we've just told them
that it does both things at the same time!
Another: There are two forms of electricity, positive electricity and
negative. NO, the two forms of electricity are static and current. NO,
there are many forms of electricity: triboelectricity, bioelectricity,
myoelectricity, piezoelectricity. NO, electricity is a single form of
energy called Electromagnetism. NO, electricity is power, it is watts,
Which is right? All and none, because the word "electricity" has multiple
contradictory definitions. None of the above statements are right because
there is no
"electricity" which is charge, energy, power, and phenomena all at once.
And all the meanings are also correct, because the word "electricity" is
commonly used to name all these different things, and these definitions
appear in the dictionary. Who are we to argue with The Dictionary?
THE "ELECTRICITY" WHICH FLOWS IN WIRES IS
SUPPLIED BY BATTERIES OR GENERATORS? Wrong.
Electric currents in copper wires are a
flow of electrons, but these electrons are not supplied by batteries.
They come from the copper atoms in the wire. The electrons were in the
circuit before the battery was connected. They were even there before the
copper was mined and made into wires! Batteries and generators do not
create these electrons, they merely pump them, and the electrons are like
a pre-existing fluid that is always found within all wires. In order to
understand electric circuits, we imagine that all the wires are
pre-filled with a sort of "liquid electricity."
To clarify this, ask yourself exactly where the "electricity" comes from
when a generator powers a light bulb. A generator takes
electrons in from one terminal and simultaneously spits them out the other
one. At the same time, the generator pushes electrons through the coil of
wire inside itself and through the rest of the circuit. Where is the
source of "electricity?" When we include
the generator in the circuit, we find that the circuit is a continuous
closed loop of wire, and we can find no original source of the
"electricity." A generator or battery is like a closed-loop pump,
but it does not supply the substance being pumped. But we were all
taught that "batteries and generators create current electricity." This
phrase forms a serious conceptual stumbling block (at least it did for me!)
To fix it, change the statement to read like this instead: "batteries and
generators cause electric charge to flow."
A battery or generator is like your
heart: it moves blood, but it does not create blood. When a generator
stops, or when the metal circuit is opened, all the electrons stop where
they are, and the wires remain filled with electric charges. But this isn't
unexpected, because the wires were full of vast quantities of charge in
the first place.
ELECTRONS IN WIRES JUMP FROM ATOM TO ATOM DURING A CURRENT? Wrong.
When separate atoms of copper are brought together to form a bulk
metal material, something unexpected happens. The outer electron of
each copper atom leaves. The outer
electrons all begin "orbiting" around and among ALL the atoms in the metal.
In a sense, the metal's electrons are "jumping" from atom to atom all the
time, even when there is no electric current applied. As a result, a
metal acts like a solid sponge which has been soaked with "liquid
charge." That's what makes wires so wonderful: they act like pre-filled
pipes. The orbiting motion of the metal's electrons is similar to the
thermal vibrations of a gas. For this reason we normally ignore
this motion, just as we ignore the vibration of air molecules when we talk
about "wind." Electrons in metals are not stuck to individual atoms,
so electrons do not need to "jump" during an electric current.
THE "ELECTRICITY" INSIDE OF WIRES MOVES AT THE SPEED OF LIGHT
In metals, electric current is a flow
of electrons. Many books claim that these electrons flow at the speed of
light. This is incorrect. Electrons actually flow quite slowly, at speeds on
the order of centimeters per minute. It's the energy in the circuit which
flows fast, not the electrons. When the electrons at one point in the
circuit are pumped, electrons in the entire loop of the circuit are forced
to flow, and energy spreads almost instantly throughout the entire circuit.
This happens even though the electrons move very slowly. Imagine a large wheel.
If you give it a
spin, the entire wheel moves as a unit, and this is how you transmit
mechanical energy almost instantly to all parts of the wheel's rim. But
the wheel itself didn't move very fast. The material of the wheel is like the
electrons in a wire. Electrical energy is like the "jerk," the mechanical
energy wave which you sent to all parts of the wheel when you gave it a
spin. Mechanical energy moves incredibly quickly to all parts of the
wheel, but the wheel's atoms didn't have to rapidly travel anywhere in
order for this to happen. MORE
THE ELECTRIC ENERGY IN A CIRCUIT FLOWS IN A CIRCLE? Wrong.
connect a light bulb to a battery, energy moves from the battery to the
bulb. This is a one-way flow. If this phenomena is examined in great
detail, we find that
electrical energy is composed of electromagnetic fields. We find
that it moves as wave energy, that it
exists only outside of the wires, and most importantly, that it TRAVELS
ONE WAY along BOTH wires on its trip from the battery to the bulb. The
energy did not travel in a circle. So, when you plug a lamp into a wall
socket, you should not imagine that the AC energy is a mysterious
invisible entity traveling back and forth inside the wires. Instead you
think of it as a mysterious invisible flow that comes out of
the outlet, runs along the outside of BOTH wires, then dives into the
filament of the light bulb.
ELECT. LEAVES ONE BATTERY PLATE, THEN RETURNS TO THE OTHER? Not
The real path of electric current is THROUGH the battery.
imply (or even state outright) that when a battery is connected in a
complete circuit, the charges flow only in the wires and within the
battery's plates, and no charges flow in the chemicals between those
is wrong. In any electric circuit, the path of the electric current is
a complete circle. It goes through all parts of the circuit including the
battery, and including the battery's electrolyte. A battery does not
supply charges, it merely pumps them.
Whenever electric charge
flows into one terminal of a battery, an equal amount of charge must flow
THROUGH the battery and back out through the other terminal. In a simple
battery/bulb circuit, the charges flow around and around the circuit,
going through both the battery and the bulb. The battery is a
ELECTRIC ENERGY IS CARRIED BY INDIVIDUAL ELECTRONS? Wrong.
Some books teach that, in a simple battery/bulb circuit, the electrons
deliver energy to the bulb, and then they return to the battery 'empty'
and need to be re-filled with energy by the battery. Some books give an
analogy with a circular train track full of freight cars waiting to be
filled. This is wrong. The energy in electric circuits is not carried by
individual electrons, it is carried by the circuit as a whole.
Here's an analogy which may help explain it: imagine a wheel that's free to
spin. For example, turn a bicycle upside-down in your mind. Give the
front tire a spin. When you spin the tire, your hand inject senergy into
the whole wheel all at once. Now put your hand lightly against a
different part of the tire so the spinning wheel is slowed and stopped by
friction. Your hand gets hot. Your hand extracts energy from the
entire wheel, all at once, and the whole wheel slows down. Finally, put
one hand lightly against the tire while you use your other hand to keep
the wheel spinning. Would it be right to tell students that the "Power" hand
fills the rubber molecules with energy, that the molecules travel to the
"friction" hand and dump their energy, then they return empty to the
"power" hand and get refilled? No, of course not! If this were true then
your "friction" hand wouldn't experience any friction until the
rubber molecules made their way around the rim. Part of the wheel would
be spinning while part would be de-energized and unmoving, and it would be
really strange to watch!
A flashlight circuit is like our bicycle wheel. The electrons in the
copper are like the rim of the wheel. The battery causes ALL the
electrons in the loop of wire to begin moving, and so it injects energy
into the WHOLE CIRCUIT all at once. As soon as the battery moves the
electrons, the distant bulb lights up. The electrons moving into the bulb's
filament are exactly the
same as the ones moving out, the bulb doesn't change them or extract stored
energy. Did your hand change the rubber tire as it rubbed on the bicycle
wheel? No, it slowed the whole wheel down, it extracted energy from the
whole wheel, and was heated by friction. Same thing with the bulb, it
slows ALL the electrons down throughout the entire circuit, and in this way
extracts energy from the whole circuit as it lights up.
BATTERIES STORE CHARGE, AND CHARGE FLOWS IN WIRES? No.
The word "charge" has more than one meaning, and the meanings contradict
each other. The "charge" in a battery is enerry (chemical energy), while
the "charge" that flows in wires is electron particles. The term "charge"
refers to several different things: to net-charge, to quantities of
charged particles, and to "charges" of energy. If you are not very
careful while using the word "charge" in teaching, you might be spreading
For example, even when metals are totally neutral, they contain vast
quantities of movable electrons. So, should we say that they contain zero
charge because they are neutral? Or, should we say that they contain a
very large amount of electric charge, because they are filled with
electrons? Don't answer yet, because your answer might be
inconsistant with how we describe capacitors (further below.)
Another: if I place an electron and
a proton together, do I have twice as much charge as before, or do I have
a neutral hydrogen atom with no charge at all? What I DO have is
confusion. Misuse of "charge" makes descriptions of electric circuits
seem complex and abstract, when the explanations are really just wrong.
Another: electric currents in wires are actually a motion of "neutralized"
charge, where every electron has a proton nearby. If we teach that a wire is
uncharged, and we ALSO teach that electric current is a flow of charge,
how can anyone make sense of a situation where a wire has no charge at
all, yet contains an enormous flow of charge? We could say "Oh, but
electric currents are usually a flow of Uncharged Charge." WHAT? What
would a student make of THAT statement? Can you see the problems that
because of the word "charge?"
Another one: if you "charge" a battery, you cause an electric
current in the electrolyte, and this electric current causes
chemical reactions to occur upon the surfaces of the battery's
plates. Chemical "fuel" acumulates, but charge does not. Chemical
energy is stored in the battery, but electrical charge is not.
When a battery is being "discharged", it's chemical fuel drives a
process which pumps charge through the battery. The fuel will
eventually be exhausted, but the total electric charge within the
battery will never change!
Another one: if you "charge" a capacitor, you move charges from one plate
to the other, and the number of charges within the device as a whole do
not change. Or from an engineer's perspective, you drive charge THROUGH
the capacitor, which causes potential across the plates to rise. But
capacitors have exactly the same total charge within them whether they are
"charged" or not! When we speak of "charging" capacitors, we've suddenly
stopped talking about charge, and started talking about electrical energy.
A "charged" capacitor has quite a bit more energy than an "uncharged" one
(but exactly the same net-charge, and the same quantity of + and -
particles.) This basic concept is very important in understanding simple
circuitry, yet it is rarely taught. The misleading term "charge" stands
in the way of understanding. I suspect that students are not the only
ones being misled. Many teachers misunderstand simple physics, and they
believe that the purpose of a capacitor is to store electric charge. Both
capacitors and inductors (coils) store ENERGY, and neither one stores
"STATIC ELECTRICITY" (CONTACT ELECTRIFICATION) IS CAUSED BY
"Static electricity" is not caused by friction. It appears when two
materials are placed into intimate contact and then separated. All that's
required is the touching. For example, when adhesive tape is placed on an
insulating surface and then peeled off, both the tape and the surface will
become electrified. No rubbing was required. Or when a plastic wheel rolls
across a rubber surface, both the surface and the wheel become electrified.
Intimate contact is sufficient, and no rubbing is needed. Of course if one of the
materials is rough or fibrous, it does not give a very large footprint of
contact area. In this case the process of rubbing one material upon another
can greatly increase the total contact area. But this rubbing is not the cause
"STATIC ELECTRICITY" IS A BUILDUP OF ELECTRONS? Wrong.
It is not a buildup of anything, it is an IMBALANCE between QUANTITIES of
positive and negative particles already present. During
contact-electrification it is usually only the negative electrons which
are moved. As negative particles are pulled away from the positive
particles, equal and opposite areas of imbalance are created. In one
place you'll have more protons than electrons, and this spot will have an
overall positive charge. Elsewhere you'll have more electrons than
protons, for an overall negative charge. You've not caused a "buildup",
you've caused an imbalance, an un-cancelling, a separation. In fact, the
science term for static electrification is CHARGE SEPARATION. The law of
Conservation of Electric Charge requires that every time you create a
region of negative charge, you must also create a region of positive
charge. In other words you must create a separation of opposite charges.
"STATIC ELECTRICITY" IS ELECTRICITY WHICH IS STATIC? Wrong.
electricity" exists whenever there are unequal amounts of positive and
negative charged particles present. It doesn't matter whether the region
of imbalance is flowing or whether it is still. Only the imbalance is
the "staticness." To say otherwise can cause several sorts of confusion.
All solid objects contain vast quantities of positive and
particles whether the objects are electrified or not. When these
quantities are not exactly equal and there is a tiny bit more positive
than negative (or vice versa), we say that the object is "electrified" or
"charged," and that "static electricity" exists. When the quantities are
equal, we say the object is "neutral" or "uncharged." "Charged" and
"uncharged" depends on the sum of opposite quantities. Since "static
electricity" is actually an imbalance in the quantities of positive and
negative, it is wrong to believe that the phenomena has anything to do
with lack of motion, with being "static." In fact, "static electricity"
can easily be made to *move* along conductive surfaces. When this
happens, it continues to display all it's normal characteristics as it
flows, so it does not stop being "static electricity" while it moves along
very non-statically! In a high voltage electrical system, the wires can
attract lint, raise hair, etc., even though there is a large current in
the wires and all the charges are flowing. And last, when any electric
circuit is broken and the charges stop flowing, they do *not* turn into
"static electricity" and begin attracting lint, etc. A disconnected wire
contains charges which are not moving, yet it contains no "static
To sort out this craziness, simply remember that "static electricity" is
not a quantity of unmoving charged particles, and "static electricity" has
nothing to do with unmovingness. If you believe that "static" and
"current" are opposite types of "electricity," you will forever be
hopelessly confused about electricity in general.
ELECTRIC CURRENT IS A FLOW OF ENERGY? Wrong.
Electric current is a very
slow motion of charged particles. On the other hand, electric energy is
made of fields and it moves fast. Electric energy and electric particles
two different things. Electric energy can move in a direction opposite to
that of the electric current. Electric energy can even move continuously
forward in the same wire where the direction of the particle motion is
back and forth at high frequency. Electric energy is composed of electric
and magnetic fields, and it exists in the space surrounding the wires.
Electric current is very different, it is (usually) a flowing motion of
electrons, and electrons are material particles, not energy particles.
Electric current is a flow of matter, not of energy. When electric
current exists in an electrolyte (in batteries, salt water, the earth, or
in your body) it is a flow of charged atoms called ions, so there is no
denying that it is a flow of material. Current is a matter flow, not an
ELECTRIC POWER FLOWS FROM GENERATOR TO CONSUMER? Wrong.
Electric power cannot be made to flow.
Power is defined as "flow of energy." Saying that power "flows" is
silly. It's as silly as saying that the stuff in a moving river is named
"current" rather than named "water." Water is real, water can flow,
flows of water are called "currents," but we should never make the mistake
of believing that water's motion (the current) is a type of substance.
confuses everyone. The issue with
energy is similar. Electrical energy is real, it is sort of like a stuff,
and it can flow along. When electric energy flows, the flow is called
"electric power." But electric power has no existence of its own.
Electric power is the rate of flow of another thing; electric
an energy current. Energy flows, but power never does, just as water
flows but "current" never does.
This affects the concepts behind the units of
electrical measurement. Energy can be measured in Joules or Ergs. The
rate of flow of energy is called Joules per second. For convenience, we
give the name "power" to this Joule/sec rate of flow, and we measure it in
Watts. Yet Watts have no physical, substance-like existence. The Joule
is the fundamental unit, and the Watt is a unit of convenience. I
believe that it is a good idea to teach only the term "Joule" in early
grades, to entirely avoid the "watt" concept. Call power by the name
second". Only introduce "watts" years later,
when the students feel a need for a convenient way to state the
"joules per second" concept. Unfortunately many textbooks do the
reverse, they keep the seemingly-complex "Joule" away from the kids, while
spreading the "watt" concept far and wide! They try to
explain that joules are simply watt-seconds! (That's watts TIMES
seconds, not watts per second.)
LIGHT AND RADIO WAVES TRAVEL AT 186,000 MILES PER SECOND?
They only travel at 186,000 miles per second while in a perfect vacuum.
Light waves travel a bit slower in the air, and it travels LOTS slower
when inside glass. Radio waves move much slower than 186,000 miles/sec
when they travel within plastic-insulated coaxial cable. The term "speed
of light" is misleading, because the complete term actually reads "speed
of light in a vacuum." There actually is no set "speed of light," for
light waves and light (and electrical energy) can travel at many different
speeds depending on the medium through which the waves propagate.
ELECTROMAGNET COILS USE UP ENERGY TO MAKE MAGNETISM? Not right.
Sustaining a magnetic field requires no energy. Coils only require energy
to initially create a magnetic field. They also require energy to defeat
electrical friction (resistance) when charges flow in wires. But if the
resistance is removed, the magnetic field can exist continuously without
energy input. If electrically frictionless superconductive wire is used,
a coil can be momentarily connected to an energy supply to create the
field. Afterwards the power supply can be removed and both the current
and the magnetic field will continue forever without further energy input.
ELECTRIC CHARGES ONLY FLOW ON THE SURFACES OF WIRES? Wrong.
ELECTRIC CHARGES ARE INVISIBLE? No.
Electric charges are very visible, even though their motion is not.
A "CONDUCTOR" IS A MATERIAL WHICH ALLOWS CHARGE TO PASS THROUGH
IT? Not exactly.
The correct definition of the word "conductor" is different than the
example, a vacuum offers no barrier to charged particles, yet vacuum is an
insulator. Vacuum allows charge to pass through, yet it is a terrible
conductor. How can we straighten out this paradox? Easy: use the
proper definition of "conductor." Fix it so it reads:
"CONDUCTOR: a material which contains movable electric charges." If
we place a Potential Difference across a vacuum, no electric current
appears. This is sensible, since there are no movable charges in a
vacuum, so there can be no electric current in a vacuum. If we place a
voltage across a piece of metal or a puddle of salt water, an electric
current will appear, since these substances are always full of movable
charges, and the "voltage pressure" causes the charges to flow. In metal,
the outer electrons of the atoms are not bound upon individual atoms but
instead can move through the material, and a voltage can drive these
"liquid" electrons along. In salt water, the individual sodium ions and
chloride ions are free to flow, and a voltage can push them so they flow
as an electric current.
THE "TWO FLUIDS" THEORY WAS DISPROVED? Not exactly.
STORM CLOUDS ARE ELECTRIFIED BY FRICTION? No.
Some books claim that
the separated charges in thunderstorms come about when clouds rub against
each other, or when the falling rain rubs against the air. This is not
correct. In fact, the true explanation for storm electrification is
unknown. There are several possible explanations, but none of them has
yet been accepted by scientists, and all the theories have problems. Here's one
So, what caused the clouds to become
electrified? Contact between dissimilar materials, followed by
wide separation of those materials.
- In a mixture of
rain and half-melted hail, the ice and water become oppositly electrified
through contact. The large hail then falls faster than the small
raindrops and spray. Two large regions appear in the cloud, one below that's
made of hail, and one above that's made of rain. These regions contain opposite
imbalances of electric charge.
BEN FRANKLIN'S KITE WAS STRUCK BY LIGHTNING? Never
believe that Ben Franklin's kite was hit by a lightning bolt, and this was
how he proved that lightning was electrical. A number of books and even
some encyclopedias say the same thing. They are wrong. When lightning
strikes a kite, the spreading electric currents in the ground can kill
anyone standing nearby, to say nothing of the person holding the string!
So what did Franklin actually do? He showed that a kite would collect a
tiny bit of electric charge out of the sky during a thunderstorm.
Electric leakage through the air caused his kite and string to become
electrified and so
the hairs on the twine stood outwards. Twine is slightly conductive, so
the imbalanced charge spread to all parts of the kite string. Franklin used
the twine to electrify a metal key, and tiny sparks could then be drawn from
the key. (He used a
metal object because sparks cannot be directly drawn from the twine, it's
not conductive enough.) This suggested that some stormclouds carry strong
electrical net-charge. It IMPLIED that lightning was just a large
The common belief that Franklin easily survived a
lightning strike is not just wrong, it is dangerous: it may convince kids
that it's OK to duplicate the kite experiment as long as they "protect"
themselves by holding a silk ribbon. Make no mistake, Franklin's
experiment was extremely dangerous, and if lightning had actually hit his
kite, he certainly would have been killed.
ELECTRICITY IS MADE OF ELECTRONS? Wrong.
Electric current in metals is a flow of electrons. But there are many
other conductors besides metals. Electric currents can also appear in
electrolytes, or in plasma. When an electric current is flowing in a neon
sign, electrons flow in one direction, while positively charged ATOMS flow
in the other. Electric currents in electrolytes (such as wet dirt and
human flesh) are flows of electrified atoms. When an electric current is
passing through a battery, it is not made of moving electrons, it is made
of moving atoms (ions.) A similar thing happens when a current passes
through the earth, the ocean, or your body. All the electric currents in
your brain and nerves are composed of moving sodium and potassium atoms.