|
Not to be confused with the Dolemite Megathread on the mineral. https://www.youtube.com/watch?v=yGWny7zK0rc
|
#
?
Jan 11, 2015 20:48
|
|
|
|
| # ? Apr 26, 2024 07:36 |
|
|
Why is electricity nearly impossible to understand? Because of... ...wide misuse of the word "electricity." Using Electricity as the single name for several completely different substance-like quantities, while at the same time expecting students to extract each differing meaning of the "electricity" from the way we use it in explanations. Unfortunately, students instead become permanently confused because they don't realize that the word has several definitions. They hear one word and assume we're talking about one single entity. As a result, they hear us describe a single "electricity-stuff" having contradictory, confusing, totally impossible behavior. ...because we misuse 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! (This is like confusion over the difference between Geology and rocks, or thinking that "Biology" and "living tissue" must be the same thing.) ...we misuse "electricity" in early grades, then we never point out our earlier misuse during more advanced grades. Students end up with misconceptions learned early on. We use "lies to children" to avoid complicated explanations, but then we're never up-front with older high-school students about the misconceptions they probably acquired in grades K-6. Why can't we specifically teach kids about this problem with the definition of the word "electricity?" ...because of our ignoring the contradiction between descriptions of various "kinds" of electricity. We insist that there are ONLY two kinds of electricity, pos and neg electricity! Then we say no, there are ONLY two kinds, static and current. Then we say no, there are many kinds of electricity: it's a CLASS OF PHENOMENON with many types, like Bioelectricity, Piezoelectricity, etc. And then: no, there is ONLY ONE kind of electromagnetic energy, and electricity is a form of energy, therefore there's only one kind of electricity. ...All these statements are both right and wrong: when used alone they are accurate only because "Electricity" has so many distinct definitions. But because these statements contradict each other, collectively they become a serious error. ...because of "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. ...because we lack rigorous dedication to truth and clarity, instead there's a cover-your-tail attitude where the confusing presence of multiple definitions of "electricity" in dictionaries is used to legitimize contradictory use of the word in classrooms. Rather than fixing the problem in classrooms, we point to the confusion in dictionaries and insist that the classroom problem is acceptable! But just because a dictionary records the various contradictory definitions, this doesn't constitute an authoritative approval of their use by teachers. ...because we use the physics-term "quantity of electricity" to legitimize other misuses of the word "electricity." Physicists use the word "electricity" in a very narrow sense, but does this mean that all OTHER definitions are OK? But "quantity of electricity" means just one thing: it means charge, measured in coulombs. In other words, physicists actually say (indirectly) that it's NOT correct to believe that electricity many other things besides coulombs of charge. They're saying that electricity is NOT joules of energy, electricity is NOT the flow of electrons, or classes of phenomena, etc. They're saying that electricity means "charge," and other definitions are popular meanings, not scientific ones. ...because of mistaken belief that "electricity" travels one way in wires, going from source to load... and at the same time believing that it travels in a circle and all returns to the source, without any being used up. ...because of mistaken belief that "electricity" travels at the speed of light, while at the same time it flows along at inches per hour as the electrons travel slowly in metals. ...mistaken belief that "electricity" alternates: flows equally 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. ...mistaken use of familiar terms with unfamiliar definition causes confusion. For example, in electrical science "AC" does not mean "alternating current". Instead it means something akin to "having changing value." So a constant voltage is called "DC" even though it's not a current. 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; DC voltage is unchanging voltage. An "AC signal" may be entirely composed of electrostatic fields and have nothing to do with current, even though we call it alternating current "AC." But if you believe that "AC" means only "Alternating Current", you will be confused by electrical explanations written by the experts. ...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 therefore we must take the word in context to see what the intended meaning is. But students don't know this, they think we're 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 substance-like 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 zero net "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 a current is a flow. Are rivers full of current? No, water. Flow of "charge" is correct, flow of "current" is not.) But lots of older literature still contains the older definition, and it 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 electron-flow, or is it 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 "wind" 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: the 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 canceled charge; neutral matter. The opposite of MOVING canceled charge is not separated charge, it is UNMOVING canceled 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 travels via 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 versus sound. Do you know that sound is not wind? TO believe that electrons flow at the speed of light is similar to believing that air must travel at 720mph along with the sound wave.
|
|
#
?
Jan 11, 2015 20:49
|
|
|
|
|
#
?
Jan 11, 2015 20:55
|
|