WHY IS ELECTRICITY IMPOSSIBLE TO UNDERSTAND?

A collection of various ideas.

(c)1995 William J. Beaty

Why is electricity impossible to understand? Because of...

MISCONCEPTIONS

Why is electricity impossible to understand? Because of...

...student misconceptions which over the years have managed to invisibly infect textbooks, and reference books, and even educators. ...widespread assumption that textbooks are nearly 100% accurate. This causes us to be overly trusting of textbooks, and so we ignore any slow increase of errors in the books. It makes us unknowningly spread the authors' misconceptions. When we do notice misconceptions, we either remain in denial about them or we minimize their importance. Our assumption that textbooks contain only minor flaws causes us to be threatened by anyone who points out serious errors or attempts to correct them. Lack of a critical viewpoint leaves textbooks wide open for creeping "infection" by increasing amounts of misconceptions. ...widespread assumption that textbooks are nearly 100% accurate. We remain in denial that they are imperfect, and this keeps students in the dark about the need to take all textbook assertions with a grain of salt. It hides from them the need to constantly examine themselves for the presence of misconceptions. As a consequence, they may never learn that hard work is required to assemble and CREATE their knowledge. Instead they end up sitting back and being spoon-fed a group of disconnected, possibly misleading facts. If we stop uncritically accepting the contents of books, we might finally become aware of the necessity of learning concepts rather than memorizing facts. ...widespread assumption that textbooks are nearly 100% accurate. This keeps students from complaining about bad textbooks and teaching. If curriculum materials are assumed to be perfect, the fault must lie with the student. But if they could instead always regard curriculum materials with a critical eye, they might demand improvements. ...assumption that student misconceptions always arise mysteriously within the students, when in fact these misconceptions are often specifically taught in earlier grades. E.g.: the constant current battery misconception. In grades K-6, kids are hammered with the concept that batteries are sources of "current electricity." High school physics teachers then complain that the kids believe that batteries always put out the same current regardless of the load. The solution isn't to figure out better teaching methods in highschool physics, the solution is to send a million complaints to the publishers of the misleading K-6 curriculum materials! ...textbooks lack discussion of common flaws and misconceptions. Books tell us all about electricity concepts, but never go into detail about possible conceptual pitfalls to avoid, and don't expose us to the idea that the recognizing and eliminating of misconceptions is a powerful learning technique. They don't stress the fact that the WRONG answers are of tremendous value, that wrong answers shouldn't be punished or hidden away in embarrassment. ...avoidance of discussion of misconceptions in the classroom. Common misconceptions aren't specifically attacked in school. If learning cannot progress until a misconception is UNlearned, then a student with a misconception can waste years in futile attempts to progress. Talented kids may needlessly abandon physics as "too hard," when the fault actually lies with their distorting "mental filter" created by an unexamined misconception. (E.g.: when kids believe that current is a substance, all accurate info on electricity will be interpreted under this assumption. As a result it will be twisted into useless garbage, while periodic textbook assertions that "current flows" will keep reinforcing the students' misconception.) ...students blaming themselves. Electricity is thought to be abstract, complicated, confusing, mysterious, and invisible, with behavior which frequently goes against common sense, and anyone who can't understand it has just not worked hard enough. No. In fact, electricity EXPLANATIONS are contradictory, confusing, needlessly abstract, and frequently go against reality and common sense. But students who have difficulties understanding them will not blame books and instructors, they will put the blame on themselves. Therefor no one will feel any need to improve the situation. ...mistaken belief that the understanding of electrical physics only involves the memorizing of right answers, and that the concept-networks, the STORYTELLING part is not important. This allows us to blithely teach sets of contradictory concepts, since each concept may be accurate when examined on its own. Example: electricity travels at nearly the speed of light (yes, this is true if "electricity" is defined as meaning "EM energy." ) Example: electricity is composed of particles called electrons (yes, if "electricity" is defined as meaning "charge") But the student will never grasp electrical physics now, because these two concepts turn to garbage when combined. ...explaining things in certain ways because it is traditional to do so, rather than explaining things in certain ways because it gets the concepts across well. "That's the way everyone does it, so it must be right." "All the textbooks do it this way, and that many books cannot be wrong." E.g.: we always say that current flows out of battery, thru lightbulb, back to battery. Why not alter this to read: charge comes out of *lightbulb,* is sucked into the battery, is spit out of other battery terminal, then flows back to the bulb? The traditional explanations muscle their way into all textbooks and wipe out creative alternate models.

THE DEFINITION OF THE WORD "ELECTRICITY"

Why is electricity impossible to understand? Because of...

...misuse of the word "electricity." Using it as a single name for several different substance-like quantities, then expecting students to extract the true meaning of "electricity" from syntax. Instead, students become permanently confused because they hear us describe a single entity having contradictory, confusing, totally impossible behavior. ...misuse of the word "electricity." Using it to name physical entities and also classes of phenomena. Students may end up believing that static, current, electrons, and protons are various types of energy! ...misuse of "electricity" in early grades, then never pointing out this misuse in more advanced grades. We're never up front with high-school students about the misconceptions they probably acquired in K-6. Why not specifically teach about this "electricity" definition problem? ...ignoring the contradiction between descriptions of "kinds" of electricity. There are two kinds, pos and neg electricity. No, there are two kinds, static and current. No, it's a phenomena with many types, like Bioelectricity, Piezoelectricity, etc. No, there is only one kind of electromagnetic energy. All these are both right and wrong: used alone they are OK, but because they contradict each other, collectively they are a serious error. ..."simplifying" a number of distinct concepts by collecting them under the single name "electricity," with the result that students come to believe in a nonexistent stuff called "electricity" which has contradictory, confusing, and impossible characteristics. ...using the presence of multiple definitions of "electricity" in dictionaries to legitimize contradictory use of the word in classrooms. But just because a dictionary records the various contradictory definitions, this doesn't constitute an authoritative approval of their use. ...using the physics term "quantity of electricity" to legitimize other misuses of the word "electricity." Physicists use the word "electricity", and this means that all other definitions are OK? But "quantity of electricity" means charge. So physicists are actually (indirectly) saying that it's incorrect to believe that electricity is anything but charge, that electricity is NOT energy, current, classes of phenomena, etc. ...mistaken belief that "electricity" travels one way, from source to load, and at the same time it travels in a circle and returns to the source. ...mistaken belief that "electricity" travels at the speed of light, while at the same time it flows along at inches per hour. ...mistaken belief that "electricity" alternates and flows back and forth at 60HZ, while at the same time it flows continuously forward from source to load. ...mistaken belief that "static electricity" is "electricity" which is static and unmoving. ...use of familiar terms with unfamiliar definition causes confusion. For example, in electrical science "AC" does not mean "alternating current". Instead it means "having changing value." So a constant voltage is called DC, and a changing voltage is called "AC," and the term "AC voltage" is commonly used. Does "AC voltage" mean "Alternating Current Voltage"? No, that would be silly. AC voltage is changing voltage. An "AC signal" may be entirely composed of electrostatic fields and have nothing to do with current. But if you believe that "AC" means only "Alternating Current", you will be confused by electrical explanations. ...wrongly assuming that students are as adept as their instructors when it comes to manipulating concepts. Some instructors know that "electricity" has multiple meanings, and therefor we must take the word in context to see what the intended meaning is. But students don't know this, they think we are using a single word, and so must be discussing a single concept. We end up convincing them that a single entity called "electricity" exists which has confusing, contradictory attributes. ...textbooks start with basic assumptions about "electricity," and then expand on these. But if the basic assumptions are never critically examined, they may or may not be correct. (Example: K-6 books assume that a single substancelike entity called "electricity" exists. Another: there are only two kinds of "electricity.") ...invisible war between old and new definitions of "electricity." The word was originally used to mean "electric fluid." As the concepts became refined, the Electric Fluid changed into "charge," so a quantity of electricity was simply a quantity of charge. But in recent decades the word has been usurped by electric companies, and now usually means "energy." But this leaves a gap, since "electric fluid", or stuff-flowing in-wires now has no common name. The word "charge" is often used instead, but this is misleading, since a wire can have no "charge" even while there is flowing charge within it. Even more often, the word "current" is incorrectly used instead of "electricity", as in "flow of current." But lots of older literature still contains the older definition, and states that "electricity flows inside of metals." Modern authors may unknowingly take older explanations to heart and believe that they were discussing energy, not knowing that the older works were discussing an entirely different "electricity" than is found in modern texts. ...incorrect popular conceptions of electricity which must be unlearned before accurate concepts can ever be understood. ...mistaking the wave for the medium. Is "electricity" the electrons, or is it the wave of energy that flows THROUGH a column of electrons. Think of how difficult it would be to understand sound waves and air pressure if we had just a single word that meant both "sound" and "air." ...mistaken belief that "generate electricity" means "create electrons." ...belief that a single "electricity-stuff" flows in circuits, when actually there are several different types of "stuff" which can flow: charge flows slowly around a circuit, while energy propagates from source to load at high speed, while net-charge and current also propagates fast in various directions. Charge flows down one wire and back up the other, while energy flows down both wires and does not return. ...mistaken belief that electric current is charges flowing inside wires at the speed of light. The charges actually flow at inches per hour. ...mistaken belief that net charge and charged particles are synonymous. However, a wire can have no net charge, yet its mobile electron-sea can flow. An "uncharged" wire which has equal amounts of protons and electrons can contain a huge electric current. Is there "charge" inside the wire? But the wire has no "charge!" ...mistaken belief that "current" and "static" are substances. The only substance here is electrons and protons. They cause the phenomena called "static" (electrons separated from protons) and "current" (groups of electrons moving in relation to groups of protons). "Static" and "current" are events. They are happenings, not substances. ...mistaken belief that a phenomenon is "made of electricity," when the phenomenon is really just "electrical." If we say that lightning is "atmospheric electricity", then we mean that it is an electrical phenomena, and should then never say that lightning is "a type of electricity," or that it is "made of electricity". Doing so would be like saying that clouds are "composed of weather," and the little droplets in a cloud are made of a liquid called "weather." ...mistakenly confusing electrical phenomena with electrical quantities. Lightning is "electricity" because it is an electrical phenomenon. But lightning is not electrical energy (the energy actually flows INTO the lightning bolt from the surrounding space) and lightning is not electric charge (the lightning can strike much faster than the electrons move, and the flowing electrons often move in the opposite direction from the direction of the lightning strike) So, lightning may be "electricity," but in the same way that batteries and bulbs are also a form of "electricity": they both are electrical. ...belief that there are only two types of electrical phenomena: static electricity and current electricity. In fact, there are many many others. Lightning is Atmospheric Electricity (and since it involves both AC and DC, electrostatics and electric current, it could also be called Impulse Electricity.) Heart-muscle phenomena is Myoelectricity. Then there's Piezoelectricity, Triboelectricity, Contact Electricity, Bioelectricity, Photoelectricity, ... ...mistaken belief that "static" and "current" are opposites. Yet pressure is not the opposite of flow. The opposite of Static (or separated +- charge) is not Current (or flowing charge.) The opposite of Static is cancelled charge; neutral matter. The opposite of MOVING cancelled charge is not separated charge, it is UNMOVING cancelled charge. ...mistaken belief that electric energy flows THROUGH an appliance and returns to the generator. Only the charges do this, not the energy. The appliance acts as an energy absorber. ...mistaken belief that energy flows out of a battery through one wire, then flows back through the other. The charges do this, while the energy flows along BOTH wires in one direction, from source to load. ...mistaken belief that, in an AC system, electric energy vibrates back and forth. It is the charges, not the energy, which vibrates like this. The energy flows forward continuously. It's like waves on water, or sound in the air: the medium wiggles as the wave-energy proceeds forward. ...wrongly describing the presence of electric current as "electricity" and the lack of current as "no electricity," when actually the flowing charges which cause the current are present whether they move or not. Analogy: when water stops flowing in a pipe, the water doesn't disappear. And when an electric current is halted, the charges remain in the wires, which is the place where they started. ...little use by educators of the wind/sound electrical analogy: - AIR is a physical substance. - Sound is a wave that propagates rapidly through a volume of air. - Wind is a flowing motion of air. - ELECTRIC CHARGES are a physical substance. - ELECTRIC ENERGY is a wave that can propagate along a column of charge. - ELECTRIC CURRENT is a flowing motion of the charge. Confusion between charge flow and energy flow is similar to confusion between wind and sound. Believing that electrons flow at the speed of light is similar to believing that air molecules travel at 720mph along with the sound wave.

ELECTRIC CURRENT

Why is electricity impossible to understand? Because of...

...mistaking the high-speed chaotic vibration of electrons for the low-speed motion of electric current. (analogy: learning that air molecules individually move very fast, and therefore believing that the earth must experience constant hurricane-speed wind.) In fact, high speed air molecules imply HOT (but unmoving) air. And the high speed of electrons acts like thermal vibrations, not like overall motion. ...mistaken belief that all electric current is a flow of electrons. This connects with the misconception that "electricity" is composed only of electrons. As a result, we tend to ignore the common non-electron currents in electrolytes, in semiconductors, nerves, the ground, oceans, batteries, corona, etc. If only charged atoms flow between the plates in a battery, we may incorrectly believe that the path of electric current is not THROUGH the battery, when in fact it is. ...mistaken belief that "electricity" is different than matter, since it obeys strange quantum-mechanical rules. This connects with the incorrect belief that "electricity" is made of electrons. But while electrons do display QM behavior, electric charge in general does not. If one believes that only electrons are important, then one may mistakenly believe that the strangely enlarged quantum-mechanical behavior of electrons applies to all currents and quantities of charge. True, electrons are so low in mass that they sometimes behave as waves, and their motion in metals is very far from classical views of physics. But ion currents are very common phenomena, and ions are massive enough that the QM behavior is vanishingly small. Many of the purported quantum-characteristics of electric current vanish when currents take place in tubes full of electrolyte. Electrons may behave strangely, but this doesn't mean that charge in general behaves strangely. Electrons may vibrate chaoticly at the speed of light in metals, but this doesn't imply that "electricity" does this in general. ...mistaken belief that no charge flows through batteries. (No electrons flow through them, so there cannot be current?) This leads to the traditional incorrect flashlight-current explanation (current comes out of battery, flows...etc.) It also leads to the misconception that batteries SUPPLY CHARGE, and have a storage place for "used" charge. This might make sense if we believe that there's no path for charge through the battery. But it's wrong, because there is a path, a path provided by flowing charged atoms. Charge flows around and around a circuit, passing THROUGH the battery over and over. ...mistaken belief that generators and batteries send out a substance called "current" to appliances. This is coupled to the mistaken belief that there is no path for current THROUGH a battery or generator. ...use of confusing term "amount of current." Current is a rate, not a substancelike quantity. We always should say "what is the rate of current," or "intensity of current", or "what is the value of current." ...wrongly mixing "quantity of a substance" with "flow rate" concepts. This mistake occurs not only in electricity. Does a shower use lots of water? Meaningless, since the length of time is not given. Is a high current a flow of "lots of electricity (charge)?" Meaningless! Is a 1000W lightbulb a user of "lots of energy?" Meaningless. A 1000W bulb uses energy at a GREATER RATE than a smaller bulb. If I turn on a small bulb for a year, versus a large bulb for a microsecond, the small bulb uses way more energy. ...incorrectly stating that electric current is "amount of electricity," rather than "amount of electricity per unit time." "Amount of charge per unit time" would be a better way to say it, of course! ...mistaken belief that since batteries and generators CAUSE electric currents, they must be PRODUCING a substance-like stuff called current. Or, since batteries and generators cause a flow of "electricity," they must be CREATING an electricity-stuff. In fact, the charges were already in the wires to begin with, and batteries/generators simply behave as charge-pump devices. ...mistaken belief that a device which causes current must be a source of charge. Belief that generators "supply current" (i.e. charges) rather than simply pumping them. This idea is supported everywhere by the term "source of current," which should more clearly be written as "cause of current." ...continuously stating that "current" flows. This tends to convince everyone of the existence of a substance-like entity called "current," and steers us away from use of the "charge flow" concept. In any piece of written text, always test for this by replacing the term "current" with the term "charge flow" to see how it reads. Most explanations will then say that "charge flow flows", but some even say that an electron is a particle of "charge flow" rather than of charge. ...taking electric current as a fundamental entity (maybe because of amp-seconds physical standard), and so not exploring deeper concepts involving electric current as flow of electric charge. ...no use of the convenient fact that rate of charge flow is proportional to charge speed. This greatly clarifies electric circuit concepts. High current is FAST charges. Zero current is STOPPED charges. ...describing a conductor as "something through which electricity can flow," rather than as "something which contains movable electricity." A vacuum is a perfect insulator, even though it offers no blockage to moving charges. But a vacuum contains no movable charge, so it insulates. ...backwards introduction of electric flow vs. electric substance. During teaching, electric current concepts are often explored first, then electric charge is introduced later if at all. As a result, students think they understand Amperes, they have little grasp of Coulombs, and in fact they may not really grasp either concept. Students end up thinking that the Amp is a fundamental unit, they ignore the Coulomb-per-second, and are confused by the Amp-second. The situation should be reversed: they should learn all about the Coulomb, hear about current only in terms of Coulombs per second, and should see the Amp-second as a strange, roundabout way of saying "coulombs." ...mistaken belief that since physics defines "quantity of electricity" in terms of ampere-seconds, quantity of electricity must somehow involve current rather than charge. No, its just that physicists in a Standards lab can measure charge flow and time more easily than they can measure net charge. It makes more sense to measure charge, then define the current as the flow of charge. Instead, the system of electrical standards first defines the current, then defines charge as a current which is on for a certain length of time. It might not make sense, but a Standards lab is after measurement accuracy, not sensible pedagogy. ...everyday electrical energy sources operate in constant-voltage mode, not constant current mode. We could say that they supply "voltage," not current. A battery is not a supplier of "current electricity," it instead supplies voltage, and various currents are DRAWN by placing various resistances between the battery leads. ...mistaken belief that batteries and generators are sources of current, when, since they are actually constant-potential systems, they are actually sources of "voltage."

ELECTRIC ENERGY

Electricity is impossible to understand because of... ...mistaken belief that electric energy is not in the electromagnetic spectrum, even though it is composed of electromagnetism. Mistaken belief that electrical energy is fundamentally different from the rest of the types of energy in the Electromagnetic spectrum. Mistaken belief that DC or 60Hz energy is "electricity," while higher frequencies are "radio." ...mistaken belief that power is a substancelike entity which can flow. Power is actually a FLOW of a substance. "Power" means energy-current. Energy can flow, and its rate of flow is called power. ...mistaken belief that electric energy is made of small particles called electrons. Actually, the fundamental unit of electrical energy is the photon, not the electron, since electrical energy is electromagnetic field/wave energy. ...mistaken belief that energy flows up one wire, through the appliance, then back down the other wire. Energy actually flows up both wires, dives into the appliance, and is converted to other types of energy (heat, motion, etc.) ...mistaken belief that electric companies sell electrons. They actually sell 60Hz "radio waves", and only use the columns of electrons in the wires to transmit the waves to the end users. ...mistaken belief that energy flows inside of wires. Electrical energy is actually electromagnetic fields. It exists as the voltage field and magnetic field which surround the wires. Electrical energy flows as a "tube" which encloses a pair of wires and exists only outside the metal. ...assumption that electrical energy is an abstract quantity which can be ignored, rather than seeing it as the EM wave energy which is sold by electric companies. ...backwards conceptual construction of power vs. energy during teaching. As a result, students think they understand Watts, none have a good grasp of Joules, and in fact they don't really grasp either concept. Students think the Watt is a fundamental unit, they ignore the Joule-per-second, and are confused by the Watt-second. The situation should be reversed: they should learn all about the Joule, hear about energy flow before learning that energy flow is the same as "power," and should see the watt-second as a strange, roundabout way of saying "joules." ...mistaken belief that individual electrons in wires carry energy along with them as they flow. The situation is really like that with sound: the energy moves as waves through a population of particles.

ELECTROSTATICS

Electricity is impossible to understand because of... ...mistaken belief that "static" and "current" are opposites. Yet pressure is not the opposite of flow. The opposite of separated charge (static) is combined charge (matter.) The opposite of moving cancelled charge (current) is unmoving cancelled charge (matter.) Pos and neg charges which are separated from each other, are not the opposite of pos and neg charges which flow relative to each other. ...mistaken belief that "static electricity" is "electricity" which is static and unmoving, rather than separated and "pressurized." ...mistaken belief that when "static" begins to flow and turns into "current," all the electrostatic phenomena must vanish. ...mistaken belief that when electrons and protons of matter are separated, they become "static" and unmoving. ...mistaking e-fields for 'static electricity,' as in: "Teacher, is the 'static' on the surface of the balloon, or is it in the space surrounding the balloon where my arm-hairs are standing up?" ...mistaken belief that "static" precludes "current" and vice versa. Actually, separated charges can be made to flow, such as in high-voltage transmission lines, and so we can have "static electricity" that flows. Conversely, when an electric current is stopped, the suddenly-unmoving charges do *not* constitute "static electricity", since there is no net charge. ...mistaken belief that "static electricity" is caused by friction, when it actually arises from charge separation. ...mistaken belief that "static electricity" only refers to dryer cling and scuffing on carpets, when in its other guise it really involves all circuitry. It's other guise is voltage. ...mistaken belief that since rubbing fur on a balloon produces electrical effects, it must be PRODUCING CHARGES. We should put much more emphasis on separation of charge, and cut out any talk of "creating charge." Charges can be created, but it takes a particle accelerator or a radioactive source to do so. ...lack of an electrical term analogous to "magnetism." E-fields are then left out of early teaching because "electricism" is not an independent topic. When a compass aligns itself, that's magnetism. When hairs align themselves in an intense, distantly generated e-field, what's it called? Not "static electricity," because the strong charge is far away. ...significant emphasis is put on teaching of magnetic fields early on, but e-fields are not taught until more advanced levels. (In grades K-6, the e-fields are hidden within the "static electricity" concept and never specifically discussed.) ...lack of early teaching of the important e-field concepts. This causes the "voltage" concept to be seen as complicated and abstract, as involving mysterious meter measurement which have no connection to anything visualizable. Yet "voltage" is "e-field", and we can draw pictures of it! ...mistaken belief that "static electricity" is caused by the static-ness or stillness of the charges. This causes the whole charge-separation concept to never be explored. ...electrostatics is skimmed over or ignored completely, yet in large part electrostatics is a study of "voltage." Skip over electrostatics, and your students will forever after be partially confused about voltage.

ELECTRIC FLUID

Electricity is impossible to understand because of... ...mistakenly believing that electric circuits are analogous to open hydraulic systems (pouring a cup of water through a pipe) when they actually behave like closed hydraulic systems: a drive-piston connected to a driven piston, with the connecting hoses pre-filled with water. This probably comes about in part when we teach that circuits are like pipes with water, but students then imagine the faucet at home, rather than the hydraulic system of a backhoe. ...mistaken belief that the fluid analogy does not apply to circuits because in wires the ENERGY flows, while in pipes the flow is of a material. Mistaken belief that the "fluid" in wires always flows at the speed of light, while in pipes the flow can be fast, slow, or stopped. Mistaken belief that the "fluid" in wires flows from the source to the load and does not return, while in pipes the water circulates around and around. This is all incorrect. Actually the "electric fluid" in wires flows slowly, not at the speed of light, just as happens in water pipes. In wires, the "electric fluid" flows slowly while the energy flows fast, just as happens in water pipes. And in wires the "electric fluid" flows slowly in a circle, just as happens in a pre-filled hydraulic system. ...the lack of a good name for "cancelled charge." When + and - come together, the result is NOT nothing. The result is matter. The result can also be the cancelled-but-mobile "electric fluid" found in all conductors. Since matter contains (is even MADE of) "cancelled charge," and since electric current in wires is a flow of "cancelled charge," we should see matter as being made of "non-moving electric current." Matter is made of "frozen electricity." The exception is conductors, which contain "liquid electricity." Some common names for the neutralized mobile charges found in conductors: Electron sea combined charge cancelled charge mobile charges mobile ions current carriers electric fluid ...early teaching about current, yet without teaching about the "substance" which flows. We shouldn't teach about "current" until AFTER we've taught the "electron sea" concept. It's like learning about ocean currents without ever learning that water exists. It makes "current" seem needlessly abstract and non-visualizable. ...mistaken belief that Ben Franklin's one-fluid theory of electricity was correct, and the two-fluid theory was wrong. In fact, matter contains pos and neg, or two kinds of "electricity." Ben though that pos and neg was a surplus or deficeit of a single sort of electric fluid. Not so, because matter turns out to be COMPOSED of positive and negative particles, so there are two kinds of electric-stuff after all. ...mistaken belief that early theories of "electric fluid" were struck down, and so "electric fluid" does not exist. Ancient experimenters believed in electric fluid, but today we know better? No. Today we know that wires contain cancelled, mobile charges. Today this is called the electron-sea of the metal, but "electric fluid" is not an incorrect way to describe it. ...misleading explanations of conductors and insulators. Instead of saying that conductors allow current, and insulators prevent it, say that conductors contain mobile charges, while insulators contain immobile charges. ...misleading explanation of a conductor as a material which passes electrons. Incorrect, since a vacuum offers no barrier to electrons, yet vacuum acts as a good insulator. The difference is that a vacuum contains no mobile charges, so when a potential difference is applied, no current results. A metal conductor doesn't pass electrons, instead, a metal conductor contains movable electrons. ...mistaken belief that electric current is a flow of energy, when it is actually a flow of matter. (our beliefs about energy tend to make us avoid ever teaching the fact that electric current is a matter flow.) ...use of the term "current carriers." This connects with the mistaken belief that current is a fundamental entity, rather than seeing charge as fundamental, and seeing current as simply a flow of charge. After all, we wouldn't say that the water molecules in a river are "water current carriers". Wires are full of mobile charges, not "current carriers." ...misleading description of wires as "hollow pipes." Ex: wires conduct electricity, metals conduct charge. Saying it this way covers up the fact that metals CONTAIN vast amounts of mobile charge already, and it paints a distorted picture of the situation. Better to say "the cancelled charge inside metals is mobile," or "the charges found in wires can be made to move." ...mistaken idea that electric charge in metals is gas-like and easily compressible. Actually, the cancelled charge within wires is fluid-like, very difficult to compress, and energy can be transported very rapidly (rigid rod analogy.) ...little use by educators of slow-electron-flow concepts. Ex: electrons flow like the minute hand on a clock, and if they were to flow fast enough that you could see a movement, that wire would be heated white hot by "friction." The electric fluid acts like tar: it stops instantly when the pressure is removed, gets hot from friction when forced to move, never moves very fast, large flows require huge pipes, small pipes are subject to very high friction, and fast movement always implies immense heating. ...mistaken "empty pipes" analogy. Wires actually behave like pipes full of water, with NO BUBBLES ANYWHERE, so when more water is pushed into one end, water immediately flows from the far end. ...mistaken "swirly water" analogy. If water is injected into a bowl, it just makes the mass of water flow in loops, and we mistakenly believe that the same holds true within pipes. But in a pipe, if more water is injected into one end, the entire column of water advances as a unit, as if it were a solid rod. In pipes, water behaves like a solid drive belt. ...mistaken belief that since electric current is invisible, the charges in an electric current are also invisible. Little use by educators of the convenient fact that electrons are visible. "Electricity" is always said to be invisible, yet the mobile charges within wires constitute a silver liquid. The milk in a glass bottle may never be seen to move when stirred (no bubbles!) but that doesn't mean that the milk itself is invisible. ...little use by educators of the drive-belt analogy. Electric circuits are like pulley/belt systems, the electron-sea within a metal wire is like the rubber belt. When one part is moved, the whole thing turns, when one spot on the belt is clamped, the whole thing stops, no rubber or electrons are consumed, the belt moves slow in a circle while the energy moves fast in waves, the belt is not invisible and neither are the charges, back-and-forth motion sometimes works better than continuous rotation (AC vs DC), friction causes heat and even light, pulleys can drive or be driven (motor/generator duality), pulleys are not a source of rubber and batteries are not a source of electrons, and when the belt or the circuit is stopped, the rubber or electrons stop in place and forever remain. And belt-systems were in actual use until supplanted with generators and wires. ...the discovery of the electron is mistakenly interpreted as suggesting that electric fluid does not exist. This is analogous to a mistaken belief that the discovery of water molecules implies that water is not a liquid. Electrons and protons are fundamental particles of the electric fluid, in a similar way that the molecule is the fundamental particle of a macroscopic material fluid.

ELECTRIC CHARGE

Electricity is impossible to understand because of... ...misuse of the word "charge," using it both to refer to a charge of energy (capacitor, battery) and a quantity of electric charge. A "charged" battery contains just as many electrons as a "discharged" battery, because batteries store their energy as chemical fuel, a battery is simply a chemically-fueled electron pump, and is "charged" with chemical fuel, not with electrical energy. A fully charged battery contains the same net electric charge as a discharged battery. (yet it contains huge amounts of matter, which is made of charge!) ...the word "charge" is used to refer to net-charge and to cancelled-charge. Students will see "charge" as following conflicting rules, yet their instructors act as if no conflict exists. But there is a conflict: an object with zero net charge is still full of charges, and an uncharged object will behave very differently that will empty space (ex: heating of neutral metal by induction, while empty space is not heated even though it is neutral.) And fast waves of net-charge can propagate through populations of barely-moving charges. Groups of charges can have zero net charge, so do they not exist? And neutral circuitry can support enormous charge flows (current) yet have no net charge at all, so how can there be chargeflow if there's no charge? ...a problem with the word "charge": an object with a dipole charge distribution is "charged," and if the charges come together , the object is "neutral," yet no charged particles were destroyed, and in fact the same quantity of charged particles are still there. So two charges far apart equals "charged," while two close together means "uncharged?" But the particles never lose their charges, so the quantity of charge never varies! ...a problem with the word "charge": when a battery is suddenly connected to a pair of long wires leading to a distant lightbulb, the wires become charged and a wave of net charge propagates along the wires at the speed of light. Yet the individual electrons, the "sea of charge," flow slowly around the circuit. So did the charge go fast or slow? Depends on whether "charge" means the electron sea, or whether it means the imbalance in quantities between the group of electrons and the group of protons in the wire. ...a problem with the word "charge": A capacitor is briefly connected to a battery, so energy is stored in the capacitor. If the leads of the capacitor are now touched together, charge moves from one plate to the other. Does the capacitor now contain less charge? Yes, because its plates are now uncharged. No, because the total quantity of electrons and protons never changed (each electron that left one plate ended up on the other plate.) A "charged" capacitor contains exactly as many electrons as an "uncharged" one. Charge imbalance is called "charge", but electrons and protons are also called "charge." ...mistakenly trying to combine the particle-physics use of "charge" with the everyday-world use. In the everyday world, when positive and negative charges are combined, the result is neutral matter. In particle physics, a combination of positive and negative charge can result in many different things (gamma rays, if positrons and electrons annihilate.) In particle physics, oppositely charged particles can be created from empty space. In the human world, neutral matter must first be present before pos. and neg. charges can be separated out: fur and rubber can "create" opposite charges, but empty space cannot. So, in the everyday world, opposite charge can fall "together," only to be separated at a later time. In particle physics, if you touch a pos to a neg, the particles are GONE. This is all a question of microscopic energy levels, of chemistry versus nuclear effects. But circuitry and electrical science involves atoms, it does not involve high energy particle annihilation. ...mistaken belief that when a positively-charged wire is connected to a negatively-charged wire only the negative net charge moves as the charges cancel. Actually the positive and negative net charges both move, they flow together and vanish. The net charge is of course an imbalance between pos. and neg. charged particles, and it is true that only the negative particles moved. Net charge is the difference between quantities of positive and negative particles, and the net charge can move differently than particles. ...ignorance of the existence of neutral charge. If we add the number of particles in equal quantities of positive and negative charges, we get a larger number: the total number of charges. If we subtract the negatives from the positives, we get zero, the net charge. The sum is linked to the amount of matter and to the amount of electron-sea able to carry current in a metal. The difference is linked to the e-field surrounding the object and to the charge-imbalance on its surface. It's wrong to call the sum and the difference both by the name "charge." For example, an uncharged wire can carry a large charge flow. Does the wire contain zero charge, since it is uncharged? Or does it contain an immense charge, since it contains moving electrons? ...mistaken belief that "electricity" involves only electrons. For example, mistaken belief that "static electricity" is the excess or deficiet of electrons. In fact, positive net charge is not a lack of electrons, it is an imbalance, it appears whenever there are more protons than electrons, and fewer electrons than protons. ...mistaken belief that "electricity" involves only electrons. For example, mistaken belief that conductors contain movable electrons. This is true only of metals, and is not true of water, human flesh, sparks, neon signs, batteries, currents in the earth, etc., etc. ...mistaken belief that "electricity" involves only electrons. For example, mistaken belief that "electricity" cannot be easily explained, since electrons are both waves and particles. But the flowing electrified atoms in a non-metal conductor are easily localized, and are even visible! The bizarre Quantum Mechanics which applies to electrons does not apply to "electricity" (meaning charges) in general.

MISC.

Electricity is impossible to understand because of... ...mistaken belief that electricity is a glowing blue "crackly" substance (mistaken belief that sparks or lightning bolts ARE electricity.) ...mistaken belief that electricity is a substance that feels tingley. But high voltage causes body hair to repel and rise. The charge itself has no "feel." And during an electric shock, the creation of ion currents in your hand will be felt by the nerves, but the ion-charges were there to begin with, and only their MOTION causes a tingling sensation. ...mistaken belief that atoms cannot be torn apart. Belief that an atom smasher is required. But all basic electrical physics is based on torn-apart electron shells. It's only the atoms' nuclei which are never disrupted. ...mistaken belief that electrons in conductors must be forcibly pulled from individual atoms before an electric current can commence. The "jumping electrons" misconception. ...mistaken belief that famous people have the "right answers." Example: if we want a good explanation of electricity, we take the writings of a famous physicist as gospel, as the single best way to explain it. But what if that physicist was a lousy educator? Fame does not make one into an ideal teacher, so in order to find a good way to teach, look for good ways to teach, don't look for famous people to copy. ...mistaken belief that in order to create teaching techniques at lower levels, we simply take the techniques used at higher levels and simplify them. However, the techniques used to teach college science students are aimed at a population which lives in a very different world than do K-6 teachers and students. Educational material tailored to train scientists is written in a different "language" than the one used at the K-6 level. Advanced material cannot just be simplified, it also must be "translated." It must use concepts relevant to the world in which its audience lives. It must do this to such a great extent that a K-6 explanation might better be created from scratch, rather than being derived from college physics. ...mistaken belief that, when it comes to explanations, there is one Right Answer. Wrongful pursuit of a single "perfect" way to explain electricity. This goes against the way people grasp concepts. To paraphrase the physicist Richard Feynman, "If you can't explain something in several independent ways, then you don't really understand it." Give up looking for the "correct" explanation, instead try to learn as many different competing explanations as possible. If one of those blind men had known that an elephant was a rope, AND a leathery wall, AND a moving hose, AND a heavy stump, he might have synthesized a sensible view of the whole animal. The situation with electricity is very similar. We can only begin to grasp the nature of that invisible elephant by acquiring many separate and seemingly incompatible viewpoint.

Some references for Misconception research

Bill Beaty's internet WWW page: http://www.eskimo.com/~billb/miscon/miscon.html Proceedings of The 2nd Int'l Seminar - Misconceptions and Educational Strategies in Science and Mathematics, July 26-29, 1987. Cornell U., Ithaca NY. Vol II and III. On microfilm from ERIC Document Repro. Services. (available on internet, see above) Mario Iona, WHY JOHNNY CAN'T LEARN PHYSICS FROM TEXTBOOKS I HAVE KNOWN Millikan Award Lecture, Am J. Phys. 55 (4) Apr 1987 pp299-307 Mario Iona, WOULD YOU BELIEVE... Series of columns in The Physics Teacher (AAPT Publication) Mario Iona, HOW SHOULD WE SAY IT? Series of columns in The Science Teacher, 1970-1972