Ampere:
Unit of electric current, the constant current which, if maintained in two straight parallel conductors of infinite length of negligible circular cross-section and placed one metre apart in a vacuum, will produce between them a force equal to 2 x 10-7 Newton per metre length
Ampere-hour:
Unit of quantity of electricity equal to 3 600 coulombs.
One unit is represented by one ampere flowing for one hour.
Coulomb:
Unit of electric charge, the quantity of electricity transported in one second by one ampere.
Farad:
Unit of electric capacitance. The capacitance of a capacitor between the plates of which there appears a difference of potential of one volt when it is charged by one coulomb of electricity. In radio practical units are the microfarad (10-6 farad), the nanofarad 10-9) and picofarad (10-12 farad)
Henry:
Unit of electrical inductance. The inductance of a closed circuit in which an electromotive force of one volt is produced when the electric current in circuit varies uniformly at the rate of one ampere per second. In radio, practical units are the microhenry (10-6 henry) and the millihenry (10-3 henry)
Hertz:
Unit of frequency. The number of repetitions of a regular occurrence in one second.
Joule:
Unit of energy. Including work and quantity of heat. The work done when the point of application of a force of one newton is displaced through a distance of one metre in the direction of the force.
Newton:
Unit of force. That force which, applied to a mass of one kilogram gives it an acceleration of one metre per second.
Ohm:
Unit of electric resistance. The resistance between two points of a conductor when a constant difference of potential of one volt applied between these two points produces in the conductor a current of one ampere.
Siemens:
Unit of conductance, the reciprocal of the ohm. A body having a resistance of 4 ohms would have a conductance of 0.25 siemens.
Tesla:
Unit of magnetic flux density, equal to one weber per square metre of circuit area.
Volt:
Unit of electric potential. The difference of electric potential between two points of a conducting wire carrying a constant current of one ampere, when the power dissipated between these points is equal to one watt.
Volt-ampere:
The product of the root-wean-square volts and root-mean-square Amperes
Watt:
Unit of power, equal to one joule per second.
A volt times amperes equals watts. (in resistive circuit)
Weber:
Unit of magnetic flux. The magnetic flux which, linking a circuit of one turn, produces in it an electromotive force of one volt as it is reduced to zero at a uniform rate in one second.
Light (velocity of):
Light waves travel at 300,000 kilometres per second (approximately). Also the velocity of radio waves..
