107 Sentences With "electromotive force" | Random Sentence Generator

The electromotive force generated by a time-varying magnetic field is often referred to as transformer emf.

The induced electromotive force is caused by a change in the magnetic flux linking the coils of an inductor.

Force is not analogous to voltage (generator voltages are often called electromotive force), but rather, it is analogous to current.

The term electromotive force was first used by Volta in a letter to Giovanni Aldini in 1798, and first appeared in a published paper in 1801 in Annales de chimie et de physique. Volta meant by this a force that was not an electrostatic force, specifically, an electrochemical force.Robert N. Varney, Leon H. Fisher, "Electromotive force: Volta's forgotten concept", American Journal of Physics, vol. 48, iss.

The transformer effect, or mutual induction, is one of the processes by which an electromotive force (e.m.f.) is induced. In a transformer, a changing electric current in a primary coil creates a changing magnetic field that induces a current in a secondary coil. This process is one of two ways of inducing an electromotive force, the other being the relative motion of a current-carrying conductor within a magnetic field.

The volt (symbol: V) is the derived unit for electric potential, electric potential difference (voltage), and electromotive force. It is named after the Italian physicist Alessandro Volta (1745–1827).

The term magnetomotive force was coined by Henry Augustus Rowland in 1880. Rowland intended this to indicate a direct analogy with electromotive force. The idea of a magnetic analogy to electromotive force can be found much earlier in the work of Michael Faraday (1791-1867) and it is hinted at by James Clerk Maxwell (1831-1879). However, Rowland coined the term and was the first to make explicit an Ohm's law for magnetic circuits in 1873.

The second role is to generate an electromotive force (EMF). In the armature, an electromotive force is created by the relative motion of the armature and the field. When the machine or motor is used as a motor, this EMF opposes the armature current, and the armature converts electrical power to mechanical power in the form of torque, and transfers it via the shaft. When the machine is used as a generator, the armature EMF drives the armature current, and the shaft's movement is converted to electrical power.

Active elements can inject power to the circuit, provide power gain, and control the current flow within the circuit. Passive networks do not contain any sources of electromotive force. They consist of passive elements like resistors and capacitors.

Magnetic induction refers to the production of an electromotive force (i.e., voltage) in a changing magnetic field. This changing magnetic field can be created by motion, either rotation (i.e. Wiegand effect and Wiegand sensors) or linear movement (i.e. vibration).

The volt (symbol: ) is the derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honour of the Italian physicist Alessandro Volta (1745–1827), who invented the voltaic pile, possibly the first chemical battery.

Ohm's law has sometimes been stated as, "for a conductor in a given state, the electromotive force is proportional to the current produced." That is, that the resistance, the ratio of the applied electromotive force (or voltage) to the current, "does not vary with the current strength ." The qualifier "in a given state" is usually interpreted as meaning "at a constant temperature," since the resistivity of materials is usually temperature dependent. Because the conduction of current is related to Joule heating of the conducting body, according to Joule's first law, the temperature of a conducting body may change when it carries a current.

The ohm is the electric resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere, the conductor not being the seat of any electromotive force. The SI definitions of the electrical units are formally equivalent to the 1908 international definitions, and so there should not have been any change in the size of the units. Nevertheless, the international ohm and the international volt were not usually realized in absolute terms but by reference to a standard resistance and a standard electromotive force respectively.

In 1894, Friedrich Ostwald concluded important studies of the conductivity and electrolytic dissociation of organic acids.Nobel Lectures, p. 170 German scientist Walther Nernst portrait in the 1910s. Walther Hermann Nernst developed the theory of the electromotive force of the voltaic cell in 1888.

549–555, May 1928 Volta distinguished electromotive force (emf) from tension (potential difference): the observed potential difference at the terminals of an electrochemical cell when it was open circuit must exactly balance the emf of the cell so that no current flowed.

The 5th harmonic causes a CEMF (counter electromotive force) in large motors which acts in the opposite direction of rotation. The CEMF is not large enough to counteract the rotation; however it does play a small role in the resulting rotating speed of the motor.

Electromotive force (EMF) measurements in a humidified oxygen concentration cell verified the high ionic nature of CsHSO4 in its superprotonic phase.Uda, Tetsuya, Dane A. Boysen, and Sossina M. Haile. "Thermodynamic, thermomechanical, and electrochemical evaluation of CsHSO 4." Solid State Ionics 176.1 (2005): 127-133.

The Daniell cell was a great improvement over the existing technology used in the early days of battery development. A later variant of the Daniell cell called the gravity cell or crowfoot cell was invented in the 1860s by a Frenchman named Callaud and became a popular choice for electrical telegraphy. The Daniell cell is also the historical basis for the contemporary definition of the volt, which is the unit of electromotive force in the International System of Units. The definitions of electrical units that were proposed at the 1881 International Conference of Electricians were designed so that the electromotive force of the Daniell cell would be about 1.0 volts.

A high impedance voltmeter is used to measure the electromotive force or potential between the two electrodes when zero or no significant current flows between them. The potentiometric response is governed by the Nernst equation in that the potential is proportional to the logarithm of the concentration of the analyte.

An active network contains at least one voltage source or current source that can supply energy to the network indefinitely. A passive network does not contain an active source. An active network contains one or more sources of electromotive force. Practical examples of such sources include a battery or a generator.

Its logo is an early depiction of Ohm's law which is "C equals E divided by R," or "the current strength in any circuit is equal to the electromotive force divided by the resistance," or the basic law of electricity. It was established in 1827 by Dr. G. S. Ohm.

All fluxes (e.g. magnetic flux, electric flux, vortex flux) make reference to a surface (S), all variables expressed by a line integral (e.g. electromotive force, velocity circulation, magnetomotive force) make reference to a line (L) and all contents (e.g. of energy, mass, entropy, etc.) make reference to a volume (V).

The term "photovoltaic" comes from the Greek φῶς (phōs) meaning "light", and from "volt", the unit of electromotive force, the volt, which in turn comes from the last name of the Italian physicist Alessandro Volta, inventor of the battery (electrochemical cell). The term "photovoltaic" has been in use in English since 1849.

Colloid vibration potential measures the AC potential difference generated between two identical relaxed electrodes, placed in the dispersion, if the latter is subjected to an ultrasonic field. When a sound wave travels through a colloidal suspension of particles whose density differs from that of the surrounding medium, inertial forces induced by the vibration of the suspension give rise to a motion of the charged particles relative to the liquid, causing an alternating electromotive force. The manifestations of this electromotive force may be measured, depending on the relation between the impedance of the suspension and that of the measuring instrument, either as colloid vibration potential or as colloid vibration current. Colloid vibration potential and current was first reported by Hermans and then independently by Rutgers in 1938.

This is often the case because voltage is taken as the reference. In circuits with primarily inductive loads, current lags the voltage. This happens because in an inductive load, it is the induced electromotive force that causes the current to flow. Note that in the definition above, the current is produced by the voltage.

By then flushing the tank with warm water, the liquid hydrazine hydrate is released. Hydrazine has a higher electromotive force of 1.56 V compared to 1.23 V for hydrogen. Hydrazine breaks down in the cell to form nitrogen and hydrogen which bonds with oxygen, releasing water. Hydrazine was used in fuel cells manufactured by Allis-Chalmers Corp.

Using this approach to justify the electromotive force equation (the precursor of the Lorentz force equation), he derived a wave equation from a set of eight equations which appeared in the paper and which included the electromotive force equation and Ampère's circuital law. Maxwell once again used the experimental results of Weber and Kohlrausch to show that this wave equation represented an electromagnetic wave that propagates at the speed of light, hence supporting the view that light is a form of electromagnetic radiation. The apparent need for a propagation medium for such Hertzian waves can be seen by the fact that they consist of orthogonal electric (E) and magnetic (B or H) waves. The E waves consist of undulating dipolar electric fields, and all such dipoles appeared to require separated and opposite electric charges.

An alternating current in a conductor produces an alternating magnetic field in and around the conductor. When the intensity of current in a conductor changes, the magnetic field also changes. The change in the magnetic field, in turn, creates an electric field which opposes the change in current intensity. This opposing electric field is called “counter-electromotive force” (back EMF).

First, it has the same drawbacks as epoxy - the quantity of solder needed to adhere the TC to a substrate varies from location to location. Second, solder is conductive and may short-circuit TCs. Generally, there is a short length of conductor that is exposed to the temperature gradient. Together, this exposed area, along with the physical weld produce an Electromotive Force (EMF).

Ostwald is especially known for his contributions to the field of electrochemistry, including important studies of the electrical conductivity and electrolytic dissociation of organic acids. Hermann Nernst developed the theory of the electromotive force of the voltaic cell in 1888. He developed methods for measuring dielectric constants and was the first to show that solvents of high dielectric constants promote the ionization of substances.

Alternating electric current flows through the solenoid, producing a changing magnetic field. This field causes an electric current to flow in a wire loop by electromagnetic induction. Magnetic fields can also be used to make electric currents. When a changing magnetic field is applied to a conductor, an electromotive force (EMF) is induced, which starts an electric current, when there is a suitable path.

Therapeutically, electromotive drug administration (EMDA) delivers a medicine or other chemical through the skin. In a manner of speaking, it is an injection without a needle, and may be described as non-invasive. It is different from dermal patches, which do not rely on an electric field. It drives a charged substance, usually a medication or bioactive agent, transdermally by repulsive electromotive force, through the skin.

In 1881, both within and across countries, different electrical units were being used. There were at least 12 different units of electromotive force, 10 different units of electric current and 15 different units of resistance. Other international Congresses were held, and sometimes referred to as International Electrical Congress, Electrical Conference, and similar variations. Secondary sources make different judgments about how to classify the Congresses.

Yavetz, pp.150–151 This preference was a result of Heaviside following James Clerk Maxwell's view of electric current, or at least, Heaviside's interpretation of it. In this view, electric current is a flow caused by the electromotive force and is the analogue of velocity caused by a mechanical force. At the capacitor, this current causes a "displacement" whose rate of change is equal to the current.

Hammond, Electromagnetism for Engineers, p. 135, Pergamon Press 1969 . A voltmeter can be used to measure the voltage (or potential difference) between two points in a system; often a common reference potential such as the ground of the system is used as one of the points. A voltage may represent either a source of energy (electromotive force) or lost, used, or stored energy (potential drop).

In electrochemistry, electrode potential is the electromotive force of a galvanic cell built from a standard reference electrode and another electrode to be characterized.IUPAC, By convention, the reference electrode is the standard hydrogen electrode (SHE). It is defined to have a potential of zero volts. The electrode potential has its origin in the potential difference developed at the interface between the electrode and the electrolyte.

Overtopping devices are long structures that use wave velocity to fill a reservoir to a greater water level than the surrounding ocean. The potential energy in the reservoir height is then captured with low-head turbines. Devices can be either onshore or floating offshore. Floating devices will have environmental concerns about the mooring system affecting benthic organisms, organisms becoming entangled, or electromotive force effects produced from subsea cables.

The electromotive force (e.m.f.) produced by a Leclanche cell is 1.4 volts, with a resistance of several ohms where a porous pot is used. It saw extensive usage in telegraphy, signaling, electric bells and similar applications where intermittent current was required and it was desirable that a battery should require little maintenance. The Leclanché battery wet cell was the forerunner of the modern zinc-carbon battery (a dry cell).

An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a coil. When the current flowing through the coil changes, the time-varying magnetic field induces an electromotive force (e.m.f.) (voltage) in the conductor, described by Faraday's law of induction.

These devices typically have one end fixed to a structure or the seabed while the other end is free to move. Energy is collected from the relative motion of the body compared to the fixed point. Oscillating wave surge converters often come in the form of floats, flaps, or membranes. Environmental concerns include minor risk of collision, artificial reefing near the fixed point, electromotive force effects from subsea cables, and energy removal effecting sediment transport.

The operating principle of electromagnetic generators was discovered in the years of 1831–1832 by Michael Faraday. The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. He also built the first electromagnetic generator, called the Faraday disk; a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet. It produced a small DC voltage.

The operating principle of electromagnetic generators was discovered in the years 1831–1832 by Michael Faraday. The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. He also built the first electromagnetic generator, called the Faraday disk, a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet. It produced a small DC voltage.

Like all dynamos, the Faraday disc converts kinetic energy to electrical energy. This machine can be analysed using Faraday's own law of electromagnetic induction. This law, in its modern form, states that the full-time derivative of the magnetic flux through a closed circuit induces an electromotive force in the circuit, which in turn drives an electric current. The surface integral that defines the magnetic flux can be rewritten as a line integral around the circuit.

In both cases, the gel forms a solid, yet porous matrix. Acrylamide, in contrast to polyacrylamide, is a neurotoxin and must be handled using appropriate safety precautions to avoid poisoning. Agarose is composed of long unbranched chains of uncharged carbohydrate without cross-links resulting in a gel with large pores allowing for the separation of macromolecules and macromolecular complexes. Electrophoresis refers to the electromotive force (EMF) that is used to move the molecules through the gel matrix.

Alternating electric current flows through the solenoid on the left, producing a changing magnetic field. This field causes, by electromagnetic induction, an electric current to flow in the wire loop on the right. Electromagnetic or magnetic induction is the production of an electromotive force across an electrical conductor in a changing magnetic field. Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction.

When a permanent magnet is moved relative to a conductor, or vice versa, an electromotive force is created. If the wire is connected through an electrical load, current will flow, and thus electrical energy is generated, converting the mechanical energy of motion to electrical energy. For example, the drum generator is based upon the figure to the bottom-right. A different implementation of this idea is the Faraday's disc, shown in simplified form on the right.

Mechanically, the device appears to be an induction motor with a magnetic material placed inside the rotor core. Heins believes that the device's potential may rest in its atypical manipulation of the back electromotive force (back EMF). A more detailed description of the device may be found in the patent application, minus supporting figures. The apparent unique quality of the Perepiteia machine is that instead of maintaining a certain state of motion, it appears to generate acceleration.

Since the armature windings of a direct-current or universal motor are moving through a magnetic field, they have a voltage induced in them. This voltage tends to oppose the motor supply voltage and so is called "back electromotive force (emf)". The voltage is proportional to the running speed of the motor. The back emf of the motor, plus the voltage drop across the winding internal resistance and brushes, must equal the voltage at the brushes.

He would work at GE for the rest of his career except for a 1922-1925 stint as the Research Division director at Edison Lamp Works. His main research interests were quantum mechanics, electromotive force, atomic structure, electron emission, unimolecular force, and high vacuum, and he authored several standard science textbooks. His textbook "Scientific Foundations of Vacuum Technique" (1922 and 1949) is a classic covering vacuum design principles. This book and the later editions are still in use today.

In electromagnetism and electronics, inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The flow of electric current creates a magnetic field around the conductor. The field strength depends on the magnitude of the current, and follows any changes in current. From Faraday's law of induction, any change in magnetic field through a circuit induces an electromotive force (EMF) (voltage) in the conductors, a process known as electromagnetic induction.

The charge separation results from the Lorentz force on the free charges in the disk. The motion is azimuthal and the field is axial, so the electromotive force is radial. The electrical contacts are usually made through a "brush" or slip ring, which results in large losses at the low voltages generated. Some of these losses can be reduced by using mercury or other easily liquefied metal or alloy (gallium, NaK) as the "brush", to provide essentially uninterrupted electrical contact.

The magnetic force () component of the Lorentz force is responsible for motional electromotive force (or motional EMF), the phenomenon underlying many electrical generators. When a conductor is moved through a magnetic field, the magnetic field exerts opposite forces on electrons and nuclei in the wire, and this creates the EMF. The term "motional EMF" is applied to this phenomenon, since the EMF is due to the motion of the wire. In other electrical generators, the magnets move, while the conductors do not.

When the electric current in a loop of wire changes, the changing current creates a changing magnetic field. A second wire in reach of this magnetic field will experience this change in magnetic field as a change in its coupled magnetic flux, d ΦB / d t. Therefore, an electromotive force is set up in the second loop called the induced EMF or transformer EMF. If the two ends of this loop are connected through an electrical load, current will flow.

Perepiteia's process begins by overloading the generator to get a current, which typically causes the wire coil to build up a large electromagnetic field. Usually, this kind of electromagnetic field creates an effect called the back electromotive force (back EMF) due to Lenz's law. The effect should repel the spinning magnets on the rotor, and slow them down until the motor stops completely, in accordance with the law of conservation of energy. However, instead of stopping, the rotor accelerates (i.e.

In the years 1831–1832, Michael Faraday discovered the operating principle of electromagnetic generators. The principle, later called Faraday's law, is that an electromotive force is generated in an electrical conductor that is subjected to a varying magnetic flux, as for example, a wire moving through a magnetic field. He also built the first electromagnetic generator, called the Faraday disk, a type of homopolar generator, using a copper disc rotating between the poles of a horseshoe magnet. It produced a small DC voltage.

The locomotives in a consisted set are switched between series and parallel mode automatically, based on speed, overhead voltage and electromotive force (EMF). The driver can select "series hold" to force some or all of the locomotives in the consisted set to remain in series mode when overhead voltage is low. If nothing is done, some of the locomotives will switch off under low overhead voltage conditions, to prevent damage to resistors, and switch on again when the voltage improves.

A Faraday disk can also be operated with neither a galvanometer nor a return path. When the disk spins, the electrons collect along the rim and leave a deficit near the axis (or the other way around). It is possible in principle to measure the distribution of charge, for example, through the electromotive force generated between the rim and the axle (though not necessarily easy). This charge separation will be proportional to the relative rotational velocity between the disk and the magnet.

Wiley New York, 1967 when they are configured such that a change in current through one wire induces a voltage across the ends of the other wire through electromagnetic induction. A changing current through the first wire creates a changing magnetic field around it by Ampere's circuital law. The changing magnetic field induces an electromotive force (EMF or voltage) in the second wire by Faraday's law of induction. The amount of inductive coupling between two conductors is measured by their mutual inductance.

Correspondingly the zinc electrode is the anode. The electrochemical reaction is: : Zn + Cu2+ → Zn2+ \+ Cu In addition, electrons flow through the external conductor, which is the primary application of the galvanic cell. As discussed under cell voltage, the electromotive force of the cell is the difference of the half-cell potentials, a measure of the relative ease of dissolution of the two electrodes into the electrolyte. The emf depends on both the electrodes and on the electrolyte, an indication that the emf is chemical in nature.

The Maxwell-Lodge effect is a phenomenon of elctromagnetic induction in which an electric charge, near a solenoid in which current changes slowly, feels an electromotive force (e.m.f.) even if the magnetic field is practically static inside and null outside. It can be considered a classical analogue of the quantum mechanical Aharonov–Bohm effect, where instead the field is exactly static inside and null outside. The term appeared in the scientific literature in a 2008 article, referring to an article of 1889 by physicist Oliver Lodge.

The standard ampere is most accurately realised using a Kibble balance, but is in practice maintained via Ohm's law from the units of electromotive force and resistance, the volt and the ohm, since the latter two can be tied to physical phenomena that are relatively easy to reproduce, the Josephson effect and the quantum Hall effect, respectively.. Techniques to establish the realisation of an ampere have a relative uncertainty of approximately a few parts in 10, and involve realisations of the watt, the ohm and the volt.

Faraday's Law of induction – that states: the total electromotive force induced in a closed circuit is proportional to the time rate of change of the total magnetic flux linking the circuit – has been largely employed in current sensing techniques. Two major sensing devices based on Faraday’s law are Current transformers (CTs) and Rogowski coils. These sensors provide an intrinsic electrical isolation between the current to be measured and the output signal, thus making these current sensing devices mandatory, where safety standards demand electrical isolation.

In an electrolytic cell a current is passed through the cell by an external voltage, causing an otherwise nonspontaneous chemical reaction to proceed. In a galvanic cell the progress of a spontaneous chemical reaction causes an electric current to flow. An equilibrium electrochemical cell is at the state between an electrolytic cell and a galvanic cell. The tendency of a spontaneous reaction to push a current through the external circuit is exactly balanced by an external voltage that is called a counter electromotive force or counter e.m.f.

A secondary cell, commonly referred to as a rechargeable battery, is an electrochemical cell that can be run as both a galvanic cell and as an electrolytic cell. This is used as a convenient way to store electricity, when current flows one way the levels of one or more chemicals build up (charging), while it is discharging they reduce and the resulting electromotive force can do work. A common secondary cell is the Lead-acid battery. This can be commonly found as car batteries.

As the DC motor starts to turn, interaction of the magnetic fields inside causes it to generate a voltage internally. This counter-electromotive force (CEMF) opposes the applied voltage and the current that flows is governed by the difference between the two. As the motor speeds up, the internally generated voltage rises, the resultant EMF falls, less current passes through the motor and the torque drops. The motor naturally stops accelerating when the drag of the train matches the torque produced by the motors.

Lodge carried out scientific investigations on the source of the electromotive force in the Voltaic cell, electrolysis, and the application of electricity to the dispersal of fog and smoke. He also made a major contribution to motoring when he patented a form of electric spark ignition for the internal combustion engine (the Lodge Igniter). Later, two of his sons developed his ideas and in 1903 founded Lodge Bros, which eventually became known as Lodge Plugs Ltd. He also made discoveries in the field of wireless transmission.

An emf is induced in a coil or conductor whenever there is change in the flux linkages. Depending on the way in which the changes are brought about, there are two types: When the conductor is moved in a stationary magnetic field to procure a change in the flux linkage, the emf is statically induced. The electromotive force generated by motion is often referred to as motional emf. When the change in flux linkage arises from a change in the magnetic field around the stationary conductor, the emf is dynamically induced.

Its construction is similar to that of a ballistic galvanometer, but its coil is suspended without any restoring forces in the suspension thread or in the current leads. The core (bobbin) of the coil is of a non-conductive material. When an electric charge is connected to the instrument, the coil starts moving in the magnetic field of the galvanometer's magnet, generating an opposing electromotive force and coming to a stop regardless of the time of the current flow. The change in the coil position is proportional only to the quantity of charge.

Transformer. A transformer is a static device that converts alternating current from one voltage level to another level (higher or lower), or to the same level, without changing the frequency. A transformer transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying electric current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (emf) or "voltage" in the secondary winding.

Parks was born in Rockwood, Pennsylvania on December 20, 1904. After attending the University of Pennsylvania for his undergraduate degree, he went to Columbia University in New York, where he earned both Master's and Ph.D. degrees in chemistry. His 1931 doctoral thesis was titled "The Activity Coefficients and Heats of Transfer of Cadmium-Sulfate from Electromotive Force Measurements at 25 and 0 Degrees". Upon graduation, Parks accepted a position on the faculty at Rhode Island State College, later renamed the University of Rhode Island, where he taught for thirty-seven years as a chemistry professor.

The inductive-discharge ignition system operates according to the rules of electromagnetism described by Faraday's Law of Induction which states that the induction of electromotive force (emf) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit. In other words, the emf generated is proportional to the rate of change of the magnetic flux. More simply stated, an electric field is induced in any system in which a magnetic field is changing with time. The change could be changes in direction of force or strength.

The original design was a saturated cadmium cell producing a reference and had the advantage of having a lower temperature coefficient than the previously used Clark cell.Robert B. Northrop Introduction to instrumentation and measurements 2nd edCRC Press, 2005 page 14 One of the great advantages of the Weston normal cell is its small change of electromotive force with change of temperature. At any temperature between and , . This temperature formula was adopted by the London conference of 1908 The temperature coefficient can be reduced by shifting to an unsaturated design, the predominant type today.

Construction was performed by the Emmerson Ferro-Conrete company of Boston. The dam itself was long, wide at the base and had a drop of . It was an Ambursen Hydraulic Construction Company (Boston type) reinforced concrete slab and buttress dam. The power plant technology and equipment were state of the art when it went into operation in 1907, with 34-inch Poole & Hunt Leffel Wheels and two 30-inch 500 hp horizontal Samson Turbines capable of an electromotive force of 11,000 volts. A 200 foot long fish ladder was constructed along the site.

In 'underhung' voice coil designs (see below), the coil is shorter than the magnetic gap, a topology that provides consistent electromotive force over a limited range of motion, known as Xmax. If the coil is overdriven it may leave the gap, generating significant distortion and losing the heat-sinking benefit of the steel, heating rapidly. Many hi-fi, and almost all professional low frequency loudspeakers (woofers) include vents in the magnet system to provide forced- air cooling of the voice coil. The pumping action of the cone and the dustcap draws in cool air and expels hot air.

The idea was the diode would rectify the Johnson noise thermal current fluctuations produced by the resistor, generating a direct current which could be used to perform work. In the detailed analysis it was shown that the thermal fluctuations within the diode generate an electromotive force that cancels the voltage from rectified current fluctuations. Therefore, just as with the ratchet, the circuit will produce no useful energy if all the components are at thermal equilibrium (at the same temperature); a DC current will be produced only when the diode is at a lower temperature than the resistor.

Since current changes are half those of a comparable two-pole motor, arcing at the brushes is consequently less. If the shaft of a DC motor is turned by an external force, the motor will act like a generator and produce an Electromotive force (EMF). During normal operation, the spinning of the motor produces a voltage, known as the counter-EMF (CEMF) or back EMF, because it opposes the applied voltage on the motor. The back EMF is the reason that the motor when free- running does not appear to have the same low electrical resistance as the wire contained in its winding.

Ohm's law first appeared in the famous book Die galvanische Kette, mathematisch bearbeitet (tr., The Galvanic Circuit Investigated Mathematically) (1827) in which he gave his complete theory of electricity. In this work, he stated his law for electromotive force acting between the extremities of any part of a circuit is the product of the strength of the current, and the resistance of that part of the circuit.Die galvanische kette: mathematisch By Georg Simon Ohm Pg. 181The galvanic circuit investigated mathematically By Georg Simon Ohm Pg. 202 The book begins with the mathematical background necessary for an understanding of the rest of the work.

The principle of Lorentz force velocimetry is based on measurements of the Lorentz force that occurs due to the flow of a conductive fluid under the influence of a variable magnetic field. According to Faraday's law, when a metal or conductive fluid moves through a magnetic field, eddy currents generate there by electromotive force in zones of maximal magnetic field gradient (in the present case in the inlet and outlet zones). Eddy current in its turn creates induced magnetic field according to Ampère's law. The interaction between eddy currents and total magnetic field gives rise to Lorentz force that breaks the flow.

By adding rolls to the armature of a motor, a larger and larger counter-electromotive force is generated on the motor. Newman outlined his claims about there being a fundamental electromagnetic interaction in all matter ultimately derived from only one type of force particle propagating at the speed of light. Newman claims that the motor derives its power by converting some of the mass of the copper in the coils into usable energy, in application of Einstein's mass–energy equivalence. According to proponents of the Energy Machine, the most crucial part of the design concerns what happens as a result of mechanical commutation.

In condensed matter physics and electrochemistry, drift current is the electric current, or movement of charge carriers, which is due to the applied electric field, often stated as the electromotive force over a given distance. When an electric field is applied across a semiconductor material, a current is produced due to the flow of charge carriers. The drift velocity is the average velocity of the charge carriers in the drift current. The drift velocity, and resulting current, is characterized by the mobility; for details, see electron mobility (for solids) or electrical mobility (for a more general discussion).

These excited electrons diffuse, and some reach the rectifying junction (usually a diode p-n junction) where they are accelerated into the p-type semiconductor material by the built-in potential (Galvani potential). This generates an electromotive force and an electrical current, and thus some of the light energy is converted into electric energy. The photovoltaic effect can also occur when two photons are absorbed simultaneously in a process called two-photon photovoltaic effect. Besides from the direct excitation of free electrons, a photovoltaic effect can arise simply due to the heating caused by absorption of the light.

Although the integrand of the line integral is time-independent, because the Faraday disc that forms part of the boundary of line integral is moving, the full-time derivative is non-zero and returns the correct value for calculating the electromotive force. Alternatively, the disc can be reduced to a conductive ring along the disc's circumference with a single metal spoke connecting the ring to the axle. The Lorentz force law is more easily used to explain the machine's behaviour. This law, formulated thirty years after Faraday's death, states that the force on an electron is proportional to the cross product of its velocity and the magnetic flux vector.

Faraday's experiment showing induction between coils of wire: The liquid battery (right) provides a current which flows through the small coil (A), creating a magnetic field. When the coils are stationary, no current is induced. But when the small coil is moved in or out of the large coil (B), the magnetic flux through the large coil changes, inducing a current which is detected by the galvanometer (G). Faraday's law of induction (briefly, Faraday's law) is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF)—a phenomenon known as electromagnetic induction.

When solids of two different materials are in contact, thermodynamic equilibrium requires that one of the solids assume a higher electrical potential than the other. This is called the contact potential. Dissimilar metals in contact produce what is known also as a contact electromotive force or Galvani potential. The magnitude of this potential difference is often expressed as a difference in Fermi levels in the two solids when they are at charge neutrality, where the Fermi level (a name for the chemical potential of an electron system ) describes the energy necessary to remove an electron from the body to some common point (such as ground).

In this way he discovered the electrochemical series, and the law that the electromotive force (emf) of a galvanic cell, consisting of a pair of metal electrodes separated by electrolyte, is the difference between their two electrode potentials (thus, two identical electrodes and a common electrolyte give zero net emf). This may be called Volta's Law of the electrochemical series. In 1800, as the result of a professional disagreement over the galvanic response advocated by Galvani, Volta invented the voltaic pile, an early electric battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and copper.

The name EMF is an abbreviation of Epsom Mad Funkers, a name taken from a fan club of the band New Order in 1989. The song "Head the Ball", which featured on the remix single release of "Lies," featured the repeating lines "electromotive force" and "ecstasy mother fucker". On the reissue of the band's 1991 album Schubert Dip, after the song "Longtime", there is a hidden track titled "EMF". In this, the chorus lyrics start off with "E for Ecstasy, M for my mind's in my feet, F from us to you" and then move on to "E for Ecstasy, M for mother fucker mother fucker, F from us to you".

The basis of all induction heating systems was discovered in 1831 by Michael Faraday. Faraday proved that by winding two coils of wire around a common magnetic core it was possible to create a momentary electromotive force in the second winding by switching the electric current in the first winding on and off. He further observed that if the current was kept constant, no EMF was induced in the second winding and that this current flowed in opposite directions subject to whether the current was increasing or decreasing in the circuit. Faraday concluded that an electric current can be produced by a changing magnetic field.

In particular, a government expert with the National Bureau of Standards felt that Adams was making unusually large claims that were not convincing. Later, the Government entered into contracts with various manufacturers to produce the battery and did not notify or seek permission from Adams. The basic idea of chemical generation of electricity was old, tracing back to the epic discovery by Italian scientist Alessandro Volta in 1795, who found that when two dissimilar metals are placed in an electrically conductive fluid an electromotive force is set up and electricity generated. The basic elements of a chemical battery are a pair of electrodes of different electrochemical properties and a liquid or moist paste electrolyte.

Zamboni's pendulum Zamboni is known to students of physics for an improved version of the dry pile (an electric battery which does not use an electrolyte) which he invented in 1812. It consists of a number of paper discs coated with zinc foil on one side and manganese dioxide on the other; the moisture of the paper serves as a conductor. By pressing a large number of such discs together in a glass tube, an electromotive force can be obtained that is sufficient to deflect the leaves of an ordinary electroscope. By bringing the terminal knobs of the pile near each other and suspending a light brass ball between them, Zamboni devised what was called an electrostatic clock.

The fundamental basis for induced voltage in a magnetic field comes from Faraday's law describing an induced electromotive force (EMF) as follows: Emf = -N (∆Φb / ∆t) (Nave, C. R. 2011). This implies that as the number of magnetic flux lines increase or decrease there is a subsequent change in induced voltage of negative or positive polarity. However the relationship of electric forces and magnetic forces were summed up in the Lorentz Force Law as: F = qE + qv x B. Here, all three forces were found to be perpendicular to each other (Nave, a, 2011). Thus Lorentz gave a specially oriented direction to each of the forces, allowing prediction of the direction of forces within the inductive pump architecture.

In 1839, Alexandre Edmond Becquerel (1820–1891) had discovered that illumination of one of two metal plates in a dilute acid changed the electromotive force (EMF). Adams, however, had a wide area of interest, chief among these was light and magnetism. Light was the focus of Adams’ research, which began in 1871, in which he studied the effects of polarization. In order to study the effects of polarization on various substances like selenium and tellurium, Adams developed a new variant of the polariscope. In doing this, he was able to research “the optical axes of biaxial crystals.” In 1876, Adams and Richard Evans Day discovered that illuminating a junction between selenium and platinum has a photovoltaic effect.

In another example, a paper in the February 11, 2011 issue of Nature Physics describes creation and measurement of long-lived magnetic monopole quasiparticle currents in spin ice. By applying a magnetic-field pulse to crystal of dysprosium titanate at 0.36 K, the authors created a relaxing magnetic current that lasted for several minutes. They measured the current by means of the electromotive force it induced in a solenoid coupled to a sensitive amplifier, and quantitatively described it using a chemical kinetic model of point-like charges obeying the Onsager–Wien mechanism of carrier dissociation and recombination. They thus derived the microscopic parameters of monopole motion in spin ice and identified the distinct roles of free and bound magnetic charges.

From 1931 to 1934, Frandsen authored or co- authored a series of experiments while at the National Bureau of Standards, the first of which was entitled, Cryoscopic Constant Heat of Fusion, and Heat Capacity of Camphor (1931). In 1932, Frederick Rossini, Washburn, and Frandsen authored "The Calorimetric Determination of the Intrinsic Energy of Gases as a Function of the Pressure." This experiment resulted in the development of the Washburn Correction for bomb calorimetry, a decrease or correction of the results of a calorimetric procedure to normal states. Frandsen also co- authored two articles with Merle Randall in 1932, The Standard Electrode Potential of Iron and the Activity Coefficient of Ferrous Chloride and Determination of the Free Energy of Ferrous Hydroxide from Measurements of Electromotive Force.

The electric dynamo uses rotating coils of wire and magnetic fields to convert mechanical rotation into a pulsing direct electric current through Faraday's law of induction. A dynamo machine consists of a stationary structure, called the stator, which provides a constant magnetic field, and a set of rotating windings called the armature which turn within that field. Due to Faraday's law of induction the motion of the wire within the magnetic field creates an electromotive force which pushes on the electrons in the metal, creating an electric current in the wire. On small machines the constant magnetic field may be provided by one or more permanent magnets; larger machines have the constant magnetic field provided by one or more electromagnets, which are usually called field coils.

Pole-mounted distribution transformer with center-tapped secondary winding used to provide "split-phase" power for residential and light commercial service, which in North America is typically rated 120/240 V. A transformer is a passive electrical device that transfers electrical energy from one electrical circuit to another, or multiple circuits. A varying current in any one coil of the transformer produces a varying magnetic flux in the transformer's core, which induces a varying electromotive force across any other coils wound around the same core. Electrical energy can be transferred between separate coils without a metallic (conductive) connection between the two circuits. Faraday's law of induction, discovered in 1831, describes the induced voltage effect in any coil due to a changing magnetic flux encircled by the coil.

The liquid junction potential interferes with the exact measurement of the electromotive force of a chemical cell, so its effect should be minimized as much as possible for accurate measurement. The most common method of eliminating the liquid junction potential is to place a salt bridge consisting of a saturated solution of potassium chloride (KCl) and ammonium nitrate (NH4NO3) with lithium acetate (CH3COOLi) between the two solutions constituting the junction. When such a bridge is used, the ions in the bridge are present in large excess at the junction and they carry almost the whole of the current across the boundary. The efficiency of KCl/NH4NO3 is connected with the fact that in these salts, the transport numbers of anions and cations are the same.

These energetically free (resistors or conductors, passive transport) or expensive (current sources, active transport) translocators set and fine tune voltage gradients – resting potentials – that are ubiquitous and essential to life's physiology, ranging from bioenergetics, motion, sensing, nutrient transport, toxins clearance, and signaling in homeostatic and disease/injury conditions. Upon stimuli or barrier breaking (short-circuit) of the membrane, ions powered by the voltage gradient (electromotive force) diffuse or leak, respectively, through the cytoplasm and interstitial fluids (conductors), generating measurable electric currents – net ion fluxes – and fields. Some ions (such as calcium) and molecules (such as hydrogen peroxide) modulate targeted translocators to produce a current or to enhance, mitigate or even reverse an initial current, being switchers. Endogenous bioelectric signals are produced in cells by the cumulative action of ion channels, pumps, and transporters.

For an open surface Σ, the electromotive force along the surface boundary, ∂Σ, is a combination of the boundary's motion, with velocity v, through a magnetic field B (illustrated by the generic F field in the diagram) and the induced electric field caused by the changing magnetic field. While the magnetic flux through a closed surface is always zero, the magnetic flux through an open surface need not be zero and is an important quantity in electromagnetism. When determining the total magnetic flux through a surface only the boundary of the surface needs to be defined, the actual shape of the surface is irrelevant and the integral over any surface sharing the same boundary will be equal. This is a direct consequence of the closed surface flux being zero.

Measured volumes of titrant are added, with thorough (magnetic) stirring, and the corresponding values of emf (electromotive force) or pH recorded. Small increments in volume should be added near the equivalence point which is found graphically by noting the burette reading corresponding to the maximum change of emf or pH per unit change of volume. When the slope of the curve is more gradual it is not always easy to locate the equivalent point by this method. However, if small increments (0.1 cm³ or less) of titrant are added near the end point of the titration and a curve of change of emf or pH per unit volume against volume of titrant is plotted, a differential curve is obtained in which the equivalence point is indicated by a peak.

After Maxwell proposed the differential equation model of the electromagnetic field in 1873, the mechanism of action of fields came into question, for instance in the Kelvin’s master class held at Johns Hopkins University in 1884 and commemorated a century later. The requirement that the equations remain consistent when viewed from various moving observers led to special relativity, a geometric theory of 4-space where intermediation is by light and radiation.What led me more or less directly to the special theory of relativity was the conviction that the electromotive force acting on a body in motion in a magnetic field was nothing else but an electric field. Albert Einstein (1953) The spacetime geometry provided a context for technical description of electric technology, especially generators, motors, and lighting at first.

Acronym Finder Definition XHHW is a designation for a specific insulation material, temperature rating, and condition of use (suitable for wet locations) for electrical wire and cable.NFPA 70 National Electrical Code (NEC) 2008 edition, Article 310.8 (B)&(C), Table 310.13(A) Wires with XHHW insulation are commonly used in the alternating current (AC) electrical distribution systems of commercial, institutional, and industrial buildings and installations, usually at voltage levels (potential difference or electromotive force) ranging from 110-600 volts. This type of insulation is used for both copper and aluminum conductors NFPA 70 National Electrical Code (NEC) 2008 edition, Article 310.14 which are either solid or stranded, depending on size. According to Underwriters Laboratories (UL) Standard 44, XHHW insulation is suitable for use in dry locations up to 90°C (194°F), or wet locations up to 75°C (167°F).

Ideal transformer and induction law A varying current in the transformer's primary winding attempts to create a varying magnetic flux in the transformer core, which is also encircled by the secondary winding. This varying flux at the secondary winding induces a varying electromotive force (EMF, voltage) in the secondary winding due to electromagnetic induction and the secondary current so produced creates a flux equal and opposite to that produced by the primary winding, in accordance with Lenz's law. The windings are wound around a core of infinitely high magnetic permeability so that all of the magnetic flux passes through both the primary and secondary windings. With a voltage source connected to the primary winding and a load connected to the secondary winding, the transformer currents flow in the indicated directions and the core magnetomotive force cancels to zero.

It is the fundamental operating principle of transformers, inductors, and many types of electrical motors, generators and solenoids. The Maxwell–Faraday equation (listed as one of Maxwell's equations) describes the fact that a spatially varying (and also possibly time-varying, depending on how a magnetic field varies in time) electric field always accompanies a time-varying magnetic field, while Faraday's law states that there is EMF (electromotive force, defined as electromagnetic work done on a unit charge when it has traveled one round of a conductive loop) on the conductive loop when the magnetic flux through the surface enclosed by the loop varies in time. Faraday's law had been discovered and one aspect of it (transformer EMF) was formulated as the Maxwell–Faraday equation later. The equation of Faraday's law can be derived by the Maxwell–Faraday equation (describing transformer EMF) and the Lorentz force (describing motional EMF).

In a zinc–carbon dry cell, the outer zinc container is the negatively charged terminal. The zinc is oxidised by the charge carrier, chloride (Cl−), via the following half-reactions: Anode (oxidation reaction, marked −) : Zn + 2 Cl− → ZnCl2 \+ 2 e− Cathode (reduction reaction, marked +) : 2 MnO2 \+ 2 NH4Cl + H2O + 2 e− → Mn2O3 \+ 2 NH4OH + 2 Cl− Other side reactions are possible, but the overall reaction in a zinc–carbon cell can be represented as : Zn + 2 MnO2 \+ 2 NH4Cl + H2O → ZnCl2 \+ Mn2O3 \+ 2 NH4OH If zinc chloride is substituted for ammonium chloride as the electrolyte, the anode reaction remains the same: : Zn + 2 Cl− → ZnCl2 \+ 2 e− and the cathode reaction produces zinc hydroxide instead of ammonium hydroxide: : 2 MnO2 \+ ZnCl2 \+ H2O + 2 e− → Mn2O3 \+ Zn(OH)2 \+ 2 Cl− giving the overall reaction : Zn + 2 MnO2 \+ H2O → Mn2O3 \+ Zn(OH)2 The battery has an electromotive force (e.m.f.) of about 1.5 V. The approximate nature of the e.m.f is related to the complexity of the cathode reaction.

Electricity became a subject of scientific interest in the late 17th century. Over the next two centuries a number of important discoveries were made including the incandescent light bulb and the voltaic pile. Probably the greatest discovery with respect to power engineering came from Michael Faraday who in 1831 discovered that a change in magnetic flux induces an electromotive force in a loop of wire--a principle known as electromagnetic induction that helps explain how generators and transformers work. In 1881 two electricians built the world's first power station at Godalming in England. The station employed two waterwheels to produce an alternating current that was used to supply seven Siemens arc lamps at 250 volts and thirty-four incandescent lamps at 40 volts. However supply was intermittent and in 1882 Thomas Edison and his company, The Edison Electric Light Company, developed the first steam-powered electric power station on Pearl Street in New York City. The Pearl Street Station consisted of several generators and initially powered around 3,000 lamps for 59 customers. The power station used direct current and operated at a single voltage.

The 19th century saw many developments of theories, and counter- theories on how electrical energy might be transmitted. In 1826 André-Marie Ampère found Ampère's circuital law showing that electric current produces a magnetic field. Michael Faraday described in 1831 with his law of induction the electromotive force driving a current in a conductor loop by a time- varying magnetic flux. Transmission of electrical energy without wires was observed by many inventors and experimenters,Luigi Galvani (1791), Peter Samuel Munk (1835), Joseph Henry (1842), Samuel Alfred Varley (1852), Edwin Houston, Elihu Thomson, Thomas Edison (1875) and David Edward Hughes (1878)T. K. Sarkar, Robert Mailloux, Arthur A. Oliner, M. Salazar-Palma, Dipak L. Sengupta, History of Wireless, John Wiley & Sons - 2006, pages 258-261Christopher H. Sterling, Encyclopedia of Radio 3-Volume, Routledge - 2004, page 831 but lack of a coherent theory attributed these phenomena vaguely to electromagnetic induction.W. Bernard Carlson, Innovation as a Social Process: Elihu Thomson and the Rise of General Electric, Cambridge University Press - 2003, pages 57-58 A concise explanation of these phenomena would come from the 1860s Maxwell's equationsShinohara (2014) Wireless Power Transfer via Radiowaves, p.

Since this energetic field is now mostly unopposed, its build-up or expulsion in one direction creates — in a manner analogous to Newton's third law of motion — a force in the opposite direction. Since there is only one moveable object in this system (the electrical conductor) for this force to work upon, the net effect is a physical force working to expel the electrical conductor out of the externally applied magnetic field in the direction opposite to that which the magnetic flux is being redirected to — in this case (motors), if the conductor is carrying conventional current upwards, and the external magnetic field is moving away from the viewer, the physical force will work to push the conductor to the left. This is the reason for torque in an electric motor. (The electric motor is then constructed so that the expulsion of the conductor out of the magnetic field causes it be placed inside the next magnetic field, and for this switching to be continued indefinitely.) Faraday's law: the induced electromotive force in a conductor is directly proportional to the rate of change of the magnetic flux in the conductor.