electro-, electr-, electri-

1. Any component in a circuit configuration used explicitly to protect other circuit components form excessive heat or current.
2. A particular type of equipment used in electric power systems to detect abnormal conditions and to initiate appropriate corrective actions.

1. A charge distribution that generates an electric field equal to that produced by two electric dipoles whose moments have the same magnitude, but extend in opposite directions a small distance apart.
2. A charge distribution that produces an electric field equivalent to what is produced by two electric dipoles whose dipole moments have the same magnitude, but point in opposite directions and which are separate from each other by a small distance.

1. A device, consisting of four electrodes arranged in alternating polarity, which focuses a beam of charged particles.
2. An instrument for focusing beams of charged particles which has four electrodes with alternately positive and negative polarity; used in electron microscopes and particle accelerators.
3. An apparatus that uses four electrodes set in an alternating positive-negative polarity series to focus the beams of charged particles employed in electron microscopes and particle accelerators.

A quantity characterizing an electric charge distribution, obtained by integrating the product of the charge density, the second power of the distance from the origin, and a spherical harmonic over the charge distribution.

1. A transition of an atom or molecule from one energy state to another, in which electric quadrupole radiation is emitted or absorbed.
2. A process in which an atom produces or absorbs quadrupole radiation when it changes from one energy level to another.

A channel used to hold and to protect wires, cables, or busbars.

A busbar is a heavy, rigid metallic conductor, usually uninsulated, which is used to carry a large electric current or to make a common connection between several electrical circuits.

A railroad having a continuous system of overhead wires or a third rail mounted alongside or between the guide rails throughout the track's length to supply electric power to a transportation system including the locomotive and cars.

Any ray of the family Torpedinidae (fish rays), capable of emitting strong electric discharges.

1 An electrical switch that allows a low power to control a higher one. A small current energizes the relay, which closes a gate, allowing a large current to flow through.
2. An electromechanical or solid-state device operated by variations in the input which, in turn, operate or control other devices connected to the output.

They are used in a wide variety of applications throughout industry; such as, in telephone exchanges, digital computers, motor and sequencing controls, and automation systems.

Highly sophisticated relays are utilized to protect electric power systems against trouble and power blackouts; as well as, to regulate and to control the generation and distribution of electrical power.

In private residences, relays are used in refrigerators, automatic washers, dishwashers, and heat and air-conditioning controls.

3. An electromechanical switch operated by a flow of electricity in one circuit and controlling the flow of electricity in another circuit.

A relay composed essentially of an electromagnet with a soft iron bar, called an armature, held close to it.

A movable contact is connected to the armature in such a way that the contact is held in its normal position by a spring and when the electromagnet is energized, it exerts a force on the armature that overcomes the pull of the spring and moves the contact so as to either complete or to break a circuit.

A relay that remains in the "on" condition after actuation until reset by applying an independent electric input.

A relay is an electrical device such that electric current flowing through it in one circuit can switch on and off a current in a second circuit

An electric furnace in which the heat is developed by the passage of current through a suitable internal resistance that may be the charge itself, a resistor embedded in the charge, or a resistor surrounding the charge.

1. The opposition that a device or material offers to the flow of direct current, equal to the voltage drop across the element divided by the current through the element.
2. The opposition to a flow of electric current through a circuit component, medium, or substance.

It is the magnitude of the actual part of the impedance and is measured in ohms.

Any form of apparatus which has a rotating member and generates, converts, transforms, or modifies electric power; such as, a motor, generator, or synchronous converter.

1. Scanning in which the required phase or amplitude of the currents fed in the various elements of the antenna array.
2. A target-seeking method in which an operator directs the radar beam by varying the phase or amplitude of the currents flowing into various components of its antenna.

An instrument powered by a small electric motor and used to shave one's face or other parts of the body.