Cast in these terms, current is the rate of electric charge motion through a conductor.Īs stated before, voltage is the measure of potential energy per unit charge available to motivate electrons from one point to another. Given point in a circuit in 1 second of time. Quantity is the capital letter "Q," with the unit of coulombsĪbbreviated by the capital letter "C." It so happens that the unit forĮlectron flow, the amp, is equal to 1 coulomb of electrons passing by a Which is a measure of electric charge proportional to the number ofĮlectrons in an imbalanced state. One foundational unit of electrical measurement, often taught in theīeginnings of electronics courses but used infrequently afterwards, is Most direct- current (DC) measurements, however, being stable over time, will be symbolized with capital letters. True for current as well, the lower-case letter "i" representing current at some instant in time. Lower-case letter "e" (or lower-case "v") to designate that value asīeing at a single moment in time. Instant it hits a power line would most likely be symbolized with a Letter "E," while the voltage peak of a lightning strike at the very Stable over a long period of time, will be symbolized with a capital For example, the voltage of a battery, which is Is described in terms of a brief period of time (called an Generator) and "V" to represent voltage across anything else.Īll of these symbols are expressed using capital letters, except in cases where a quantity (especially voltage or current) Reserve "E" to represent voltage across a source (such as a battery or "E" and "V" are interchangeable for the most part, although some texts Stands for "Electromotive force." From what research I've been able toĭo, there seems to be some dispute over the meaning of "I." The symbols "Intensity" (of electron flow), and the other symbol for voltage, "E," The "I" is thought to have been meant to represent "R" for resistance and the "V" for voltage are both self-explanatory, The mathematical symbol for each quantity is meaningful as well. Ampere, the volt after the Italian Alessandro Volta, and the ohm after the German Georg Simon Ohm. Letter Ω, just a character in a foreign alphabet (apologies to any Greek readers here).Įach unit of measurement is named after a famous experimenter in electricity: The amp after the Frenchman Andre M. Yes, that strange-looking "horseshoe" symbol is the capital Greek The "unitĪbbreviation" for each quantity represents the alphabetical symbol usedĪs a shorthand notation for its particular unit of measurement. Physics and engineering, and are internationally recognized. Standardized letters like these are common in the disciplines of
Letter used to represent that quantity in an algebraic equation. The "symbol" given for each quantity is the standard alphabetical Here are the standard units of measurement forĮlectrical current, voltage, and resistance: "pound" or "gram." For temperature we might use degrees Fahrenheit orĭegrees Celsius. Way that we might quantify mass, temperature, volume, length, or any To be able to make meaningful statements about these quantities inĬircuits, we need to be able to describe their quantities in the same Resistance are often stated as being "between" or "across" two points For this reason, the quantities of voltage and Just like voltage, resistance is a quantity relativeīetween two points. In a circuit depends on the amount of voltage available to motivate theĮlectrons, and also the amount of resistance in the circuit to opposeĮlectron flow.
Without reference to two particular points, the term "voltage" has no meaning.įree electrons tend to move through conductors with some degree ofįriction, or opposition to motion. Of how much potential energy exists to move electrons from one particular point in that circuit to another particular point. Voltage being present in a circuit, we are referring to the measurement Voltage is a specific measure of potential energy that is always The force motivating electrons to "flow" in a circuit is called voltage. This continuous movement ofįree electrons through the conductors of a circuit is called a current, and it is often referred to in terms of "flow," just like the flow of a liquid through a hollow pipe.
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Volume I - DC » OHM's LAW » How voltage, current, and resistance relateĪn electric circuit is formed when a conductive path is created toĪllow free electrons to continuously move.