# Electric current

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An electric current is the rate of flow of electric charge past a point or region.wikipedia
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### Ammeter

microammetermoving coil meterampere-meter
The ampere (symbol: A) is an SI base unit Electric current is measured using a device called an ammeter.
An ammeter (from Ampere Meter) is a measuring instrument used to measure the current in a circuit.

### Ampere

AmAamp
The SI unit of electric current is the ampere, which is the flow of electric charge across a surface at the rate of one coulomb per second. where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms.
The ampere ( or (UK), symbol: A), often shortened to "amp", is the base unit of electric current in the International System of Units (SI).

### Power supply

power suppliesPSUpower supply unit
This often corresponds to the actual current direction, because in many circuits the power supply voltage is positive with respect to ground.
The primary function of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load.

### André-Marie Ampère

AmpèreAmpereAmpère, André-Marie
symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating Ampère's force law (1820).
The SI unit of measurement of electric current, the ampere, is named after him.

### Alternating current

ACalternating-currentalternating
In alternating current (AC) systems, the movement of electric charge periodically reverses direction.
Alternating current (AC) is an electric current which periodically reverses direction, in contrast to direct current (DC) which flows only in one direction.

### Electron

electronse − electron mass
In electric circuits this charge is often carried by electrons moving through a wire.
By measuring the amount of deflection for a given level of current, in 1890 Schuster was able to estimate the charge-to-mass ratio of the ray components.

### Volt

VkVvolts
where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms.
One volt is defined as the difference in electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points.

### Charge carrier

charge carrierscarriersminority carrier
The moving charged particles in an electric current are called charge carriers.
In a conducting medium, an electric field can exert force on these free particles, causing a net motion of the particles through the medium; this is what constitutes an electric current.

### Semiconductor

In other materials, notably the semiconductors, the charge carriers can be positive or negative, depending on the dopant used. In electronics, other forms of electric current include the flow of electrons through resistors or through the vacuum in a vacuum tube, the flow of ions inside a battery or a neuron, and the flow of holes within metals and semiconductors. Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams.

### Solar cell

solar cellsphotovoltaic cellphotovoltaic cells
Direct current is produced by sources such as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type.
It is a form of photoelectric cell, defined as a device whose electrical characteristics, such as current, voltage, or resistance, vary when exposed to light.

### Electric charge

chargeelectrical chargecharged
In alternating current (AC) systems, the movement of electric charge periodically reverses direction. An electric current is the rate of flow of electric charge past a point or region.
The motion of electrons in conductive metals in a specific direction is known as electric current.

### Voltage

potential differenceVvoltages
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points.
Electric potential differences between points can be caused by electric charge, by electric current through a magnetic field, by time-varying magnetic fields, or some combination of these three.

### Static electricity

static chargestaticstatic electric
Natural observable examples of electrical current include lightning, static electric discharge, and the solar wind, the source of the polar auroras.
The charge remains until it is able to move away by means of an electric current or electrical discharge.

### Waveform

waveformswave formwave-form
The usual waveform of an AC power circuit is a sine wave.
In electronics, the term is usually applied to periodically varying voltages, currents, or electromagnetic fields.

### Commutator (electric)

commutatorcommutatorscommutation
Direct current is produced by sources such as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type.
A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit.

### Direct current

DCdirect-currentDC current
In contrast, direct current (DC) is the unidirectional flow of electric charge, or a system in which the movement of electric charge is in one direction only.
The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage.

### Eddy current

eddy currentseddyeddy-current
Eddy currents are electric currents that occur in conductors exposed to changing magnetic fields.
Eddy currents (also called Foucault's currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor according to Faraday's law of induction.

### Electric power

powerelectrical powerelectrical
AC is the form of electric power most commonly delivered to businesses and residences.
*Passive devices or loads: When electric charges move through a potential difference from a higher to a lower voltage, that is when conventional current (positive charge) moves from the positive terminal to the negative terminal, work is done by the charges on the device.

### Vacuum tube

vacuum tubestubethermionic valve
In electronics, other forms of electric current include the flow of electrons through resistors or through the vacuum in a vacuum tube, the flow of ions inside a battery or a neuron, and the flow of holes within metals and semiconductors.
In electronics, a vacuum tube, an electron tube, or valve (British usage) or, colloquially, a tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.

### Galvanometer

D'Arsonval galvanometertangent galvanometernull detector
Electric current can be directly measured with a galvanometer, but this method involves breaking the electrical circuit, which is sometimes inconvenient.
A galvanometer is an electromechanical instrument used for detecting and indicating an electric current.

### Hall effect

Hall coefficientHall-effectCorbino effect
The Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor, transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current.

### AC power

reactive powerACapparent power
The usual waveform of an AC power circuit is a sine wave.
Apparent power is often expressed in volt-amperes (VA) since it is the product of rms voltage and rms current.

### Shunt (electrical)

shuntshuntsshunt resistor
In electronics, a shunt is a device which creates a low-resistance path for electric current, to allow it to pass around another point in the circuit.

### Cathode ray

electron beamcathode rayselectron beams
Direct current may flow in a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams.
Modern vacuum tubes use thermionic emission, in which the cathode is made of a thin wire filament which is heated by a separate electric current passing through it.

### Dynamo

dynamo-electric machinedynamosbrush arc light dynamos
Direct current is produced by sources such as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type.
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 and Lenz's law.