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Resistance
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Capacitance
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Coulombs per second is shortened to the term ampere (named after a French Physicist, Andre Ampere (1775-1836)). So 1 ampere of electric current flows when 1 Coulomb of electric charge moves past any given point in one second of time. Ampere includes the quantity of electrons ( Coulomb) and the time factor (1 Second). The letter "I" is the symbol used to represent current in electrical engineering. Thus if I=5 amperes, then 5 Coulombs of electrical charge pass a given point every second ! |
Electric current moves at 186,000 miles per second, the speed of light. In radio, the amount of current flow may be hundreds of amperes in some transmitting equipment, but usually it is a fraction of an ampere. Units such as milliampere (.001 amperes) and microamperes (.000001 amperes) are commonly found.
(Here is a handy on-line tool for Electric Current Unit Conversion.... check it out! )
Electric current is invisible, but its presence can be detected because of its effects. The greater the current, the more pronounced the effects.
There are three basic effects an electric current can exhibit. They are:
1. HEAT EFFECT: Electric current flowing through a conductor raises its temperature. The temperature rise can be insignificant or high enough to cause the conductor to glow red or white hot, i.e. toaster wire, light bulb filament.
2. MAGNETIC EFFECT: Every conductor through which an electric current is flowing is surrounded by an invisible energy known as the magnetic field. Moving electrons create this field and the strength of the field depends upon the strength of the current. A magnetic field is capable of applying mechanical forces on metals and on electrons moving in nearby conductors. This fact is important to remember in any study of radio theory.
3. CHEMICAL EFFECT: Electrons passing through fluids can cause the decomposition of the fluid as takes place during hydrolysis when water is broken down into hydrogen and oxygen. Electric current passing through acids in which certain metals are present can result in the decomposition of the metal, i.e. the electroplating process.
