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Alternating current Alternating current occurs when charge in a conductor reverses its direction of travel ar regular intervals. A transformer can be used to alter the voltage of an AC current which allows it to be increased for transmission and distribution. This is necessary because high voltage transmissions are more efficient than low voltage ones over long distances due to the loss caused by conductor resistance decreases as the voltage increases. The effective voltage of an AC utility power source is usually considered to be the DC voltage that would produce the same power dissipation as heat assuming a pure resistance. Direct Current DC (Direct current) is the is the flow of electricity in one direction unlike an AC current. The intensity of the current can vary, but the direction of movement stays the same at all times. Direct current is produced by electrochemical and photovoltaic cells and batteries. In contrast, the electricity available from the mains in most countries is AC. AC can be converted to DC using a power supply consisting of a transformer, a rectifier (which prevents the flow of current from reversing), and a filter (which eliminates current pulsations in the output of the rectifier). Virtually all electronic and computer hardware needs DC to function. Most solid-state equipment requires between 1.5 and 13.5 volts. Current demands can range from practically zero for an electronic wristwatch to more than 100 amperes for a radio communications power amplifier. Equipment using vacuum tubes, such as a high-power radio or television broadcast transmitter or a CRT(cathode-ray tube) display, require from about 150 volts to several thousand volts DC. Current Current is a flow of electrical charge carriers, usually electrons or electron-deficient atoms. The common symbol for current is the uppercase letter I. The standard unit is the ampere, symbolized by A. Physicists consider current to flow from relatively positive points to relatively negative points; this is called conventional current or Franklin current. Ohm's Law Ohm's Law is the mathematical relationship among electric current, resistance, and voltage. The principle is named after the German scientist Georg Simon Ohm. Mathematically, Ohm's Law for DC circuits can be stated as three equations, If R = Ohms, I = Amperes, and E = Volts then Ohms can be calculated. E = IR I = E/R R = E/I When making calculations, compatible units must be used, if the units are other than ohms (for resistance), amperes (for current), and volts (for voltage). These unit conversions should be made before calculations are done. Ampere An ampere is a unit of measure of the rate of electron flow or current in an electrical conductor. One ampere of current represents one coulomb of electrical charge (6.24 x 1018 charge carriers) moving past a specific point in one second.
Approximate Word count = 1806
Approximate Pages = 7.2
(250 words per page double spaced)
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