UTY02

• Electricity


  The science dealing with the physical phenomena arising from the existence and interaction of electric charges
• Electric charge


  The intrinsic property of matter giving rise to all electric phenomena, occurring in two forms arbitrarily given positive and negative algebraic signs and measured in coulombs
• Coulomb


  The SI unit of electric charge, equal to the quantity of electricity transferred across a conductor by a current of one ampere in one second
• Electromotive force


  The energy per unit charge available for conversion from a chemical, mechanical, or other form of energy into electrical energy
• Potential difference


  The voltage difference between two points that represents the work involved in the transfer of a unit charge from one point to the other
• Potential


  The work required to move a unit charge from a reference point to a designated point
• Battery


  A group of two or more cells connected together to produce electric current
• Cell


  A device for converting chemical into electrical energy, usually consisting of a receptacle with electrodes in an electrolyte
• Electrode


  A conductor through which a current enters or leaves a nonmetallic medium
• Anode


  The negative terminal of a primary cell or storage battery
• Cathode


  The positive terminal of a primary cell or storage battery
• Voltage


  Potential difference or electromotive force expressed in volts; analogous to pressure in water flow
• Volt


  The SI unit of potential difference and electromotive force, defined as the difference of electric potential between two points of a conductor carrying a constant current of one ampere
• Circuit


  The complete path of an electric current, including the source of electric energy
• Series


  An arrangement of components in an electric circuit in which the same current flows through each component in turn without branching
• Parallel


  An arrangement of components in an electric circuit in which all positive terminals are connected to one conductor and all negative terminals are connected to a second conductor, the same voltage being applied to each component
• Power


  The product of potential difference and current in a direct-current circuit; in an alternating current circuit, power is equal to the product of the effective voltage, the effective current and the cosine of the phase angle between current and voltage
• Watt


  The SI unit of power, equal to one joule per second or to the power represented by a current of one ampere flowing across a potential difference of one volt
• Wattage


  An amount of power, especially the power required to operate an electrical device or appliance, expressed in watts
• Kilowatt


  A unit of power, equal to 1,000 watts
• Current


  The rate of flow of electric charge in a circuit per unit time, measured in amperes
• Ampere


  The basic SI unit of electric current, equivalent to the flow of one coulomb per second or to the steady current produced by one volt applied across a resistance of one ohm
• Resistance


  The opposition of a conductor to the flow of current, causing some of the electric energy to be transformed into heat and usually measured in ohms
• Ohm


  The SI unit of electrical resistance, equal to the resistance of a conductor in which a potential difference of one volt produces a current of one ampere
• Joule’s law


  The principle that the rate of production of heat by a direct current is directly proportional to the resistance of the circuit and to the square of the current
• Resistivity


  The resistance per unit length of a substance with a unit cross-sectional area
• Conductivity


  A measure of the ability of a substance to conduct electric current, equal to the reciprocal of the resistivity of the substance
• Generator


  A machine that converts mechanical energy into electrical energy
• Alternator


  A generator for producing alternating current
• Electric motor


  A machine that converts electric power into mechanical energy
• Armature


  The main current-carrying winding of a motor or generator in which electromotive force is induced
• Brush


  A copper or carbon conductor serving to maintain electric contact between fixed and moving elements in a motor or generator
• Direct current


  An electric current flowing in one direction only and having a magnitude that does not vary or varies only slightly
• Alternating current


  An electric current that reverses direction at regularly recurring intervals, having a magnitude that varies in a sinusoidal manner
• Volt-ampere


  A unit of electric measurement, equal to the product of one volt and one ampere, equivalent to one watt for direct-current systems and a unit of apparent power for alternating current systems
• Transformer


  An electric device consisting of two or more windings wound on the same core, which employs the principle of mutual induction to convert variations of alternating current in a primary circuit into variations of voltage and current in a secondary circuit
• Step-up transformer


  A transformer having fewer turns in the primary winding than in the secondary, serving to transform low voltage to high voltage
• Step-down transformer


  A transformer having a greater number of turns in the primary winding than in the secondary, serving to transform high voltage to low voltage
• Line voltage


  The voltage supplied by a power line, measured at the point of use
• Service conductor


  Any of several conductors extending from a main power line or transformer to the service equipment of a building