coulomb | unit of energy measurement | Britannica.com unit of energy measurement weber Coulomb, unit of electric charge in the metre - kilogram - second - ampere system, the basis of the SI system of physical units. The coulomb is defined as the quantity of electricity transported in one second by a current of one ampere. Named for the 18th–19th-century French physicist Charles-Augustin de Coulomb , it is approximately equivalent to 6.24 × 1018 protons. Learn More in these related articles: metre (m) in measurement, fundamental unit of length in the metric system and in the International Systems of Units (SI). It is equal to approximately 39.37 inches in the British Imperial and United States Customary systems. The metre was historically defined by the French Academy of Sciences in 1791 as 1... kilogram (kg) basic unit of mass in the metric system, equal to the mass of the international prototype of the kilogram, a platinum-iridium cylinder kept at the International Bureau of Weights and Measures laboratory at Sèvres, France. A kilogram is very nearly equal (it was originally intended to be...

2 References found in Britannica Articles Assorted References work of Coulomb (in Charles-Augustin de Coulomb ) External Links Corrections? Updates? Help us improve this article! Contact our editors with your feedback. MEDIA FOR: You have successfully emailed this. Error when sending the email. Try again later. Edit Mode Submit Tips For Editing We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind. Encyclopædia Britannica articles are written in a neutral objective tone for a general audience. You may find it helpful to search within the site to see how similar or related subjects are covered. Any text you add should be original, not copied from other sources. At the bottom of the article, feel free to list any sources that support your changes, so that we can fully understand their context. (Internet URLs are the best.) Your contribution may be further edited by our staff, and its publication is subject to our final approval. Unfortunately, our editorial approach may not be able to accommodate all contributions. Submit Thank You for Your Contribution! Our editors will review what you've submitted, and if it meets our criteria, we'll add it to the article.

Please note that our editors may make some formatting changes or correct spelling or grammatical errors, and may also contact you if any clarifications are needed. Uh Oh There was a problem with your submission. Please try again later. Close Date Published: February 25, 2016 URL: Access Date: January 20, 2017 Share Coulomb - definition of coulomb by The Free Dictionary Coulomb - definition of coulomb by The Free Dictionary (ko͞o′lŏm′, -lōm′) n. Abbr. C The basic unit of electric charge, equal to the quantity of charge transferred in one second by a steady current of one ampere, and equivalent to 6.2415 × 1018 elementary charges, where one elementary charge is the charge of a proton or the negative of the charge of an electron. A coulomb's value in the International System differs very slightly from that in the meter-kilogram-second-ampere system of units. See Table at measurement . adj.

also cou·lom·bic (ko͞o-lŏm′bĭk, -lōm′-) Of or relating to the Coulomb force. [After Charles Augustin de Coulomb.] Coulomb (ˈkuːlɒm; French kulɔ̃) n (Biography) Charles Augustin de (ʃarl oɡystɛ̃ də). 1736–1806, French physicist: made many discoveries in the field of electricity and magnetism coulomb (ˈkuːlɒm) n (Units) the derived SI unit of electric charge; the quantity of electricity transported in one second by a current of 1 ampere. Symbol: C [C19: named after Charles Augustin de Coulomb] cou•lomb (ˈku lɒm, -loʊm, kuˈlɒm, -ˈloʊm) n. the SI unit of quantity of electricity, equal to the quantity of electric charge transferred in one second across a conductor in which there is a constant current of one ampere.

Abbr.: C [1880–85; after Coulomb ] (ˈku lɒm, -loʊm, kuˈlɒm, -ˈloʊm) n. Charles Augustin de, 1736–1806, French physicist and inventor. cou·lomb (ko͞o′lŏm′, ko͞o′lōm′) A unit used to measure electric charge. One coulomb is equal to the quantity of charge that passes a point in an electric circuit in one second when a current of one ampere is flowing through the circuit. coulomb The unit of electric charge, defined as the quantity of electricity conveyed by one ampere in one second. ThesaurusAntonymsRelated WordsSynonymsLegend: Electrical units of measurment (V,A,Ω,W,...) Volt (V) Volt is the electrical unit of voltage . One volt is the energy of 1 joule that is consumed when electric charge of 1 coulomb flows in the circuit. 1V = 1J / 1C Ampere (A) Ampere is the electrical unit of electrical current .

It measures the amount of electrical charge that flows in an electrical circuit per 1 second. 1A = 1C / 1s Ohm is the electrical unit of resistance. 1Ω = 1V / 1A Watt is the electrical unit of electric power . It measures the rate of consumed energy. 1W = 1J / 1s 1W = 1V ï¿½ 1A Decibel-milliwatt (dBm) Decibel-milliwatt or dBm is a unit of electric power , measured with logarithmic scale referenced to 1mW. 10dBm = 10 ï¿½ log10(10mW / 1mW) Decibel-Watt (dBW) Decibel-watt or dBW is a unit of electric power , measured with logarithmic scale referenced to 1W. 10dBW = 10 ï¿½ log10(10W / 1W) Farad (F) Farad is the unit of capacitance. It represents the amount of electric charge in coulombs that is stored per 1 volt.

1F = 1C / 1V Henry is the unit of inductance. 1H = 1Wb / 1A siemens is the unit of conductance, which is the opposite of resistance. 1S = 1 / 1Ω Coulomb is the unit of electric charge . 1C = 6.238792×1018 electron charges Ampere-hour (Ah) Ampere-hour is a unit of electric charge . One ampere-hour is the electric charge that flow in electrical circuit, when a current of 1 ampere is applied for 1 hour. 1Ah = 1A ï¿½ 1hour One ampere-hour is equal to 3600 coulombs. 1Ah = 3600C Tesla is the unit of magnetic field. 1T = 1Wb / 1m2 Weber is the unit of magnetic flux. 1Wb = 1V ï¿½ 1s Joule (J) Joule is the unit of energy. 1J = 1 kg ï¿½ 1(m / s)2 Kilowatt-hour (kWh) Kilowatt-hour is a unit of energy.

1kWh = 1kW ï¿½ 1h = 1000W ï¿½ 1h Kilovolt-amps (kVA) Kilovolt-amps is a unit of power. 1kVA = 1kV ï¿½ 1A = 1000 ï¿½ 1V ï¿½ 1A Hertz (Hz) Hertz is the unit of frequency. It measures the number of cycles per second. 1 Hz = 1 cycles / s What is coulomb? - Definition from WhatIs.com pneumatics The coulomb (symbolized C) is the standard unit of electric charge in the International System of Units ( SI ). It is a dimensionless quantity, sharing this aspect with the mole . A quantity of 1 C is equal to approximately 6.24 x 1018, or 6.24 quintillion. In terms of SI base units, the coulomb is the equivalent of one ampere -second. Conversely, an electric current of A represents 1 C of unit electric charge carriers flowing past a specific point in 1 s.

The unit electric charge is the amount of charge contained in a single electron . Thus, 6.24 x 1018 electrons have 1 C of charge. This is also true of 6.24 x 1018 positrons or 6.24 x 1018 protons, although these two types of particle carry charge of opposite polarity to that of the electron. The force with which two electrically charged bodies attract or repel one another depends on the product of the charges (in coulombs) in both objects, and also on the distance between the objects. If the polarities are the same (negative/negative or positive/positive), the so-called coulomb force is repulsive; if the polarities are opposite (negative/positive or positive/negative), the force is attractive. For any two charged bodies, the coulomb force decreases in proportion to the square of the distance between their charge centers.

This was last updated in September 2005 Continue Reading About coulomb Coulomb | Define Coulomb at Dictionary.com coulomb [koo-lom, -lohm, koo-lom, -lohm] /ˈku lɒm, -loʊm, kuˈlɒm, -ˈloʊm/ Spell noun 1. the standard unit of quanitity of electricity in the International System of Units (SI), equal to the quantity of charge transferred in one second across a conductor in which there is a constant current of one ampere. Abbreviation: C. [koo-lom, -lohm, koo-lom, -lohm; French koo-lawn] /ˈku lɒm, -loʊm, kuˈlɒm, -ˈloʊm; French kuˈlɔ̃/ Spell [sharl oh-gy-stan duh] /ʃarl oʊ güˈstɛ̃ də/ (Show IPA), 1736–1806, French physicist and inventor.

Dictionary.com Unabridged Examples from the Web for coulomb Expand The coulomb is the unit quantity of electricity just as the unit of quantity of water is the gallon. Physics Willis Eugene Tower A delicate instrument, invented by coulomb, for measuring the intensities of the electrical and magnetic forces. British Dictionary definitions for coulomb Expand noun 1. the derived SI unit of electric charge; the quantity of electricity transported in one second by a current of 1 ampere C Word Origin C19: named after Charles Augustin de Coulomb Coulomb noun 1. Charles Augustin de (ʃarl oɡystɛ̃ də). 1736–1806, French physicist: made many discoveries in the field of electricity and magnetism Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd.

1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Word Origin and History for coulomb Expand n. 1881, named for French chemist Charles-Augustin de Coulomb (1736-1806), who devised a method of measuring electrical quantity. It is the quantity of electricity conveyed in 1 second by a current of 1 ampere. The name is a French form of Columbus. Online Etymology Dictionary, © 2010 Douglas Harper coulomb cou·lomb (kōō'lŏm', -lōm') n. Abbr. C The unit of electrical charge in the meter-kilogram-second system equal to the quantity of charge transferred in one second by a steady current of one ampere. The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company.

Published by Houghton Mifflin Company. 'lŏm', k 'lōm') The SI derived unit used to measure electric charge. One coulomb is equal to the quantity of charge that passes through a cross-section of a conductor in one second, given a current of one ampere. Coulomb, Charles Augustin de 1736-1806. French physicist who was a pioneer in the study of magnetism and electricity. He is best known for the formulation of Coulomb's law, which he developed as a result of his investigations of Joseph Priestley's work on electrical repulsion. Coulomb also established a law governing the attraction and repulsion of magnetic poles. The coulomb unit of electric charge is named for him. The American Heritage® Science Dictionary Copyright © 2002. Published by Houghton Mifflin. All rights reserved. Convert nanocoulomb [nC] <—> coulomb [C] • Electrical Engineering • Electric Charge • Compact Calculator Learn technical English with this video! Overview This may sound surprising, but we encounter static electricity daily — when stroking our cat, brushing our hair, or putting on a sweater made of synthetic materials.

We thus become static electricity generators. We are actually “enveloped” in static electricity every day, because we live in the strong electrostatic field of the Earth. This field is generated because the Earth is surrounded by the upper layer of the atmosphere, the ionosphere, which conducts electricity. Ionosphere was formed under the influence of the cosmic radiation, and has its own charge. While engaging in everyday activities such as warming up food, we generally do not think that we are essentially using static electricity when igniting the gas on the gas burner with automatic ignition or with an electric lighter. Examples of Static Electricity Lightning on Earth. View from the International Space Station. Photographs by NASA. As children and sometimes into adulthood, we are afraid of thunder, even though thunder by itself is harmless and is merely the nature’s “sound effect” to lightning — a fascinating display caused by the static electricity in the atmosphere. It is simply our instinct to fear thunder — this fear makes us aware of the dangers of the lightning. Lightning is not the only such phenomenon that generates both fear and fascination. In the past when sailboats were common, sailors were awe-struck by St.

Elmo’s fire on the masts of their sailboats, caused by static electricity in the atmosphere. Electricity had its place in mythology as well — people associated lightning with ancient gods: Greek Zeus, Roman Jupiter, Scandinavian Thor, or Slavic Perun. An Air Canada aircraft is grounded while being refueled People have been fascinated with electricity for many centuries, and we often do not realize that the scientists, who studied static electricity and came to many useful conclusions about its properties, saved us from the horrors of fires and explosions. We have tamed static electricity by using lightning rods for our buildings and grounding devices to ensure safety of fuel trucks. Despite this, static electricity continues to disrupt our daily life by creating interference with radio signals. This is not surprising: at each instant in time there are up to 2000 thunderstorms that generate up to 50 lightnings per second. People have been studying static electricity since ancient times. Even the word “electron” came to us from Ancient Greek, although it did not have the current meaning back then. Instead it meant amber — a material that electrifies really well when rubbed (ancient Greek ἤλεκτρον — amber).

Unfortunately, the study of static electricity had victims: while conducting experiments Georg Wilhelm Richmann, a Russian scientist, was killed by lightning, the most deadly phenomenon caused by static electricity. Static Electricity and the Weather Generally speaking the mechanism by which the storm cloud gathers an electric charge is very similar to the process of electrification of a hair brush — charging in both cases happens due to friction. Ice particles in the cloud are formed from the water drops, as they are moved from the lower and warmer layers of the atmosphere up to the colder ones. These ice particles collide as they move. Bigger particles become negatively charged, while the smaller ones get a positive charge. The weight difference of the particles causes the movement of particles within the cloud, with the heavier ones gathering at the bottom and the lighter smaller ones — at the top of the cloud. This movement is called an updraft. Even though the cloud as a whole is neutrally charged, the bottom of it is charged negatively, and the top — positively.

Benjamin Franklin on the $100 bill Just as the electrified hair brush attracts a balloon because the electric charge is concentrated on the side of it that is closer to the brush, so does the storm cloud, which creates a positive charge on the surface of the Earth. As the cloud develops into a storm cloud, the charge grows, and the field density increases. Once this density reaches a critical point for the given weather conditions, an electrostatic discharge, that is, lightning, occurs. Trust in God, but ground your house! Humanity owes the invention of the lightning rod to Benjamin Franklin, a scientist who later became the President of Pennsylvania, and first U.S. Postmaster General. Since his invention the number of fires, caused by the lightning striking buildings has been mostly eradicated. Franklin decided not to patent his invention, making it available for all people on the planet. Sometimes lightnings can be useful. For example, historically iron and copper mining specialists that worked in the Ural mines in Russia determined the presence of these ores by the frequency of lightning strikes in a given area. Leyden jars. Canada Science and Technology Museum.

When talking about scientists that studied electrostatic phenomena, it is important to remember the British physicist Michael Faraday, the father of electrodynamics, as well as the Dutch scientist Pieter van Musschenbroek, the inventor of the prototype of a capacitor — the famous Leyden jar. While watching car races such as the Deutsche Tourenwagen Masters (DTM), IndyCar, or Formula 1, we often do not realize that car mechanics choose whether or not to use rain tires based on the information collected by the local weather radars. This data is in turn based on the electrical characteristics of the clouds above the area. Weather radar at Toronto Pearson airport Static electricity is both our friend and our foe. Electrical engineers have to work around it. Lightning can damage circuit boards located in the vicinity of the strike — usually it is their input stages that are damaged in this event. The engineers have to use grounding straps when fixing these circuit boards. When the grounding equipment does not operate as expected, it can cause serious accidents and even catastrophes with numerous casualties, from fires to explosions of entire factories.

Static Electricity in Medicine Despite numerous problems that static electricity causes, it helps people with life-threatening ventricular fibrillation, which is a condition in which there are chaotic contractions of the heart muscle. The heart can be restored to normal functioning by subjecting it to a small electrostatic charge. This is done by a device called the defibrillator. It is important to note that this device does not restart the heart but stops the incorrect rhythm and is used along with other treatments. The scene depicting the “return to life” of a patient with acute heart failure by using a defibrillator is a classic for movies of a certain genre. The movies often make a mistake of showing the revival of a patient with no heartbeat (as seen by the straight line on the monitor) by using the defibrillator. This is incorrect — the defibrillator cannot “restart” a heart. Static dischargers on the wing of a Boeing 738-800 are designed to control corona discharge into the atmosphere and providing reliable work of aircraft onboard navigation and communication equipment Other Examples We should not forget about the necessity to connect all separate components of an airplane together by bonding strips to protect them from static electricity.

To do so all of the metal parts in the airplane including the engine are connected to each other to make an electrically-integral structure. All trailing edges of wings, flaps, ailerons, elevator and the rudder of the airplane are outfitted with static dischargers to ensure that the static electricity, generated during the flight as a consequence of friction between the airplane and the air, is discharged into the air. This reduces the interference from static electricity with the work of the onboard electronic devices. Electrostatic experiments are some of the most exciting in the section on electricity of the high school Physics courses: there are the hair standing straight up, the balloons that chase hair brushes, the mysterious glow of fluorescent lights not connected to the power source, and many more! This glow saves lives of electricians working with high voltage power lines and power distribution units. The most important aspect of static electricity is its role in the life on Earth. Scientists came to believe that it is thanks to electrostatics that the life as we know it emerged.

Early experiments in the mid-20th century showed that sending an electrical charge through a mix of gases similar to the mix present in the atmosphere of the Earth around the time when life emerged, generates an amino acid, which is one of the building blocks of life. Uninterruptible power supply units or UPS are used to safeguard against loss of power or power surges such as those that can happen during the lightning strike. In order to tame static electricity it is important to know the difference of potentials or the electric voltage. Devices called voltmeters have been invented for this purpose. The notion of electric voltage was introduced by the 19th century Italian scientist Alessandro Volta, and the units that measure voltage were called “volts” after him. Before the invention of voltmeters, different devices called galvanometers were used to measure electrostatic voltage. The term “galvanometer” was derived from the surname of another Italian scientist, Luigi Galvani. Unfortunately, the measuring mechanism of an electrodynamic system used in galvanometers distorted the measurements. Study of Static Electricity It is believed that the systematic study of electrostatics started in the 18th century with the work of the French scientist Charles-Augustin de Coulomb.

In particular, he was the one who introduced the notion of electric charge and formulated the law that describes the interaction between electric charges. The unit that quantifies the amount of electricity, namely the electrical charge, is named coulomb (C) after him. To be fair we should mention that a British scientist Henry Cavendish also worked on similar problems before Coulomb, but he did not publish this work during his lifetime — it was published by his heirs about 100 years later. Earlier work on electricity allowed physicists George Green, Carl Friedrich Gauss, and Siméon Denis Poisson to create an elegant mathematical model for electricity. We use it till this day. This model is based on the concept of an electron, which is a subatomic particle. Every atom contains electrons and they can be easily separated from the atomic structure when external forces are applied. The principle of repulsion of similarly charged particles and attraction of particles with opposite charges is also fundamental in our understanding of electricity. Measuring Electrical Values Digital multimeter can measure current, voltage, resistance and check transistors One of the first devices used to quantify electricity was developed by the British physicist Abraham Bennet. It consisted of two pieces of gold foil inside a glass container.

Since then, measuring devices have greatly improved, and now they can measure in units as small as nanocoulombs (nC). Using very precise measuring devices, the Russian physicist Abram Ioffe and the American physicist Robert Andrews Millikan were able to measure the electric charge of an electron. With the development of digital technologies, highly sensitive measuring devices were built. They have unique characteristics, which allow them to work with minimal and almost undetectable distortions. This is due to their high input resistance. Besides measuring voltage, these devices can measure other important characteristics at a wide measurement range, such as ohmic resistance and the flow of electric current. The most advanced devices are called multimeters or multitesters for their range of functionality. They also measure the frequency of alternating current and capacitance of capacitors. In addition they allow the user to test transistors and even to measure temperature. Generally, modern devices have safety features that prevent the device from breaking if it is used incorrectly. They are small and easy to use. They are also safe — the safety is checked under strenuous work conditions using a battery of tests. They are also tested for accuracy. At the end of the tests the device receives a certificate indicating its safety and accuracy.

This article was written by Sergey Akishkin You can hide articles if you use this converter often. Cookies must be allowed in your browser. You may be interested in another converters in the Electrical Engineering group: Learn Technical English with Our Videos! You can use this online converter to convert between several hundred units (including metric, British and American) in 76 categories, or several thousand pairs including acceleration, area, electrical, energy, force, length, light, mass, mass flow, density, specific volume, power, pressure, stress, temperature, time, torque, velocity, viscosity, volume and capacity, volume flow, and more. Note: Integers (numbers without a decimal period or exponent notation) are considered accurate up to 15 digits and the maximum number of digits after the decimal point is 10. In this calculator, E notation is used to represent numbers that are too small or too large. E notation is an alternative format of the scientific notation a · 10x. For example: 1,103,000 = 1.103 · 106 = 1.103E+6.

Here E (from exponent) represents “· 10^”, that is “times ten raised to the power of”. E-notation is commonly used in calculators and by scientists, mathematicians and engineers. Select the unit to convert from in the left box containing the list of units. Select the unit to convert to in the right box containing the list of units. Enter the value (for example “15”) into the left From box. The result will appear in the Result box and in the To box. Alternatively, you can enter the value into the right To box and read the result of conversion in the From and Result boxes. If you have noticed an error in the text or calculations, or you need another converter, which you did not find here, please let us know ! Measurement unit conversion: coulomb Measurement unit conversion: coulomb The SI derived unit for electric charge is the coulomb. ›› Convert coulomb to another unit Convert coulomb to Valid units must be of the electric charge type.

You can use this form to select from known units: Convert coulomb to I'm feeling lucky, show me some random units ›› Definition: Coulomb he coulomb, symbol C, is the SI unit of electric charge, and is defined in terms of the ampere: 1 coulomb is the amount of electric charge (quantity of electricity) carried by a current of 1 ampere flowing for 1 second. It is also about 6.241506ï¿½1018 times the charge of an electron. It is named after Charles-Augustin de Coulomb (1736-1806). SI Units Explained - The ampere Go to the SI Units Explained Page Electric current is a flow of electricity through a medium and its SI unit is the ampere, with the symbol A. The flow is typically through a wire and composed of electrons, the tiny particles that make up electricity. For most practical purposes the ampere is a measure of the amount of electric charge passing a particular point in a given time . To illustrate the ampere we can ask the simple question: how many electrons does it take to make a cup of tea?

The ampere (A) How many atoms electrons are needed to make a cup of tea? The next SI Unit is the metre (m) . Find out how long it would take to walk around planet Earth. Other SI units are available from the menus at the top of the page. We more often than not refer to the ampere simply as an amp, and an amp has the units of 1 coulomb per second. Mathematically we can show this as 1 A = 1 C/s. But what is a coulomb? It is the derived SI unit of electric charge and 1 coulomb contains around 6.241 x 1018 electrons. Let's look at that number written out fully: 624,100,000,000,000,000 Remember that this is the amount of electrons passing a single point in a wire every single second . There are so many of them that it's natural to assume that they are whizzing past at some tremendous speed, but that's not the case. In fact, they are moving very slowly - typically only about a metre or two an hour, but they are very, very small.

So we know that 1 A = 1 C/s and we know how many electrons there are in a coulomb. A typical kettle will draw about 2000 watts of power, and how many coulombs per second that is depends on the voltage being used. In England, a country associated with drinking copious amounts of tea, the mains voltage is 230v so we will use that as our example. Amps can be calculated from watts divided by voltage so in England (and the rest of the UK) a 2000W kettle will use around: 2000W / 230v = 8.7A In other words around 8.7 coulombs per second . It takes about 90 seconds to boil enough water for a cup of tea, and, as stated above, an amp is a coulomb per second, so to boil the water in the kettle it will need: 90 s x 8.7 A = 783 coulombs We can now finally work out how many electrons we need to make a cup of tea.

The answer is simply the number of coulombs multiplied by the number of electrons in a coulomb: 783 x 6.241 x 1018 = 4.887 x 1021 electrons Writing that out fully we get: 4,887,000,000,000,000,000,000 electrons Why not try working out how long it would take to count that number of electrons at a rate of one electron a second? (Answer at the bottom of the page.) In the US the mains voltage is lower at 120v. That means even more electrons are needed to boil the same amount of water. Carrying out the mathematics (as above) it takes about 16.7 amps, or about 9.380 x 1021 electrons. Note that same amount of power is used in both the UK and US examples. The difference is that the number of electrons passing a single point in the wire is greater in the US than the UK, but the energy each electron possesses is lower.

We can either use a lot of low energy electrons, or fewer electrons but each with higher energy. Finally, note that the actual number of electrons will be a little different (by percentage) to those calculated here. For a more precise answer we would need to measure the initial temperature of the water and take electrical resistance into account, as well as a number of other factors. Still, the final answer will be close enough and certainly gives a sense of understanding electric current and its SI unit, the ampere. Answer to question: A year is about 60 x 60 x 24 x 365 = 31500000 seconds . So it would take 4887000000000000000000 divided by 31500000 = 1500000000000000 years to count the electrons at one a second, 24 hours a day, 365 days a year (you can take a day off each leap year...) To put this into context, it would take about 1.5 x 1015 years to count the electrons.

The age of the Universe is about 13.7 x 109 years, so it would take longer to count the electrons than the Universe has so far been around for. Best get started now... Seconds in a Day etc. Electric current Electric current is a flow of electricity through a medium and its SI unit is the ampere, with the symbol A. The flow is typically through a wire and composed of electrons, the tiny particles that make up electricity. For most practical purposes the ampere is a measure of the amount of electric charge passing a particular point in a given time . To illustrate the ampere we can ask the simple question: how many electrons does it take to make a cup of tea? The ampere (A) How many atoms electrons are needed to make a cup of tea? The next SI Unit is the metre (m) . Find out how long it would take to walk around planet Earth. Other SI units are available from the menus at the top of the page. We more often than not refer to the ampere simply as an amp, and an amp has the units of 1 coulomb per second. Mathematically we can show this as 1 A = 1 C/s.

But what is a coulomb? It is the derived SI unit of electric charge and 1 coulomb contains around 6.241 x 1018 electrons. Let's look at that number written out fully: 624,100,000,000,000,000 Remember that this is the amount of electrons passing a single point in a wire every single second . There are so many of them that it's natural to assume that they are whizzing past at some tremendous speed, but that's not the case. In fact, they are moving very slowly - typically only about a metre or two an hour, but they are very, very small. So we know that 1 A = 1 C/s and we know how many electrons there are in a coulomb. A typical kettle will draw about 2000 watts of power, and how many coulombs per second that is depends on the voltage being used. In England, a country associated with drinking copious amounts of tea, the mains voltage is 230v so we will use that as our example.

Amps can be calculated from watts divided by voltage so in England (and the rest of the UK) a 2000W kettle will use around: 2000W / 230v = 8.7A In other words around 8.7 coulombs per second . It takes about 90 seconds to boil enough water for a cup of tea, and, as stated above, an amp is a coulomb per second, so to boil the water in the kettle it will need: 90 s x 8.7 A = 783 coulombs We can now finally work out how many electrons we need to make a cup of tea.

The answer is simply the number of coulombs multiplied by the number of electrons in a coulomb: 783 x 6.241 x 1018 = 4.887 x 1021 electrons Writing that out fully we get: 4,887,000,000,000,000,000,000 electrons Why not try working out how long it would take to count that number of electrons at a rate of one electron a second? (Answer at the bottom of the page.) In the US the mains voltage is lower at 120v. That means even more electrons are needed to boil the same amount of water. Carrying out the mathematics (as above) it takes about 16.7 amps, or about 9.380 x 1021 electrons. Note that same amount of power is used in both the UK and US examples. The difference is that the number of electrons passing a single point in the wire is greater in the US than the UK, but the energy each electron possesses is lower.

We can either use a lot of low energy electrons, or fewer electrons but each with higher energy. Finally, note that the actual number of electrons will be a little different (by percentage) to those calculated here. For a more precise answer we would need to measure the initial temperature of the water and take electrical resistance into account, as well as a number of other factors. Still, the final answer will be close enough and certainly gives a sense of understanding electric current and its SI unit, the ampere. Answer to question: A year is about 60 x 60 x 24 x 365 = 31500000 seconds . So it would take 4887000000000000000000 divided by 31500000 = 1500000000000000 years to count the electrons at one a second, 24 hours a day, 365 days a year (you can take a day off each leap year...) To put this into context, it would take about 1.5 x 1015 years to count the electrons.

The age of the Universe is about 13.7 x 109 years, so it would take longer to count the electrons than the Universe has so far been around for. Best get started now... Advertisement Coulomb (unit) - definition of Coulomb (unit) by The Free Dictionary Coulomb (unit) - definition of Coulomb (unit) by The Free Dictionary (ko͞o′lŏm′, -lōm′) n. Abbr. C The basic unit of electric charge, equal to the quantity of charge transferred in one second by a steady current of one ampere, and equivalent to 6.2415 × 1018 elementary charges, where one elementary charge is the charge of a proton or the negative of the charge of an electron. A coulomb's value in the International System differs very slightly from that in the meter-kilogram-second-ampere system of units. See Table at measurement . adj. also cou·lom·bic (ko͞o-lŏm′bĭk, -lōm′-) Of or relating to the Coulomb force.

[After Charles Augustin de Coulomb.] Coulomb (ˈkuːlɒm; French kulɔ̃) n (Biography) Charles Augustin de (ʃarl oɡystɛ̃ də). 1736–1806, French physicist: made many discoveries in the field of electricity and magnetism coulomb (ˈkuːlɒm) n (Units) the derived SI unit of electric charge; the quantity of electricity transported in one second by a current of 1 ampere. Symbol: C [C19: named after Charles Augustin de Coulomb] cou•lomb (ˈku lɒm, -loʊm, kuˈlɒm, -ˈloʊm) n. the SI unit of quantity of electricity, equal to the quantity of electric charge transferred in one second across a conductor in which there is a constant current of one ampere. Abbr.: C [1880–85; after Coulomb ] (ˈku lɒm, -loʊm, kuˈlɒm, -ˈloʊm) n. Charles Augustin de, 1736–1806, French physicist and inventor.

cou·lomb (ko͞o′lŏm′, ko͞o′lōm′) A unit used to measure electric charge. One coulomb is equal to the quantity of charge that passes a point in an electric circuit in one second when a current of one ampere is flowing through the circuit. coulomb The unit of electric charge, defined as the quantity of electricity conveyed by one ampere in one second. ThesaurusAntonymsRelated WordsSynonymsLegend:

Question: Coulomb is a unit of measurement of electrical?
Answer: Charge