Volts, Ohms and Amps

VOLTS (V) describes the "pressure" or force of the current. It is also known as Electromotive Force (EMF). One VOLT is the amount of force required to move 1 amp though a resistance of 1 Ohm. To measure the amount of VOLTS present in a cicuit a Voltmeter is used.

OHMS (R) describes the resistance to the flow of electrons. A peice of metal allows the flow of electrons therefore has very little resistance. A piece of wood is a different matter, here the flow of electrons is limited, therefore the resistance is high. To measure resistance an Ohmmeter is used. With this kind of meter all sources of outside currents must be removed, as the Ohmmeter itself produces current to send though the cicuit being tested.

AMPS (I) describes the amount of flow or "current" in a cicuit. This "current" is the movement of electrons along a conductor. One AMP means that 6.28 Billon, Billon electrons have pased a single point in one second. The measurement of AMPS is done with a Ammeter. Also there are two kinds of "current" AC and DC.

AC and DC The flow of electrons determines the type of current. In a DC (Direct current) the electrons flow only one way. This is the type of current used on automobiles 12v DC it is the current produced and stored by a Battery. In AC (Alternating current) the electrons flow back and forth, first one way then the other (see Hertz). The Alternator driven by the engine produces AC current, it is changed to DC current before it enters the electrical system of the automobile. DC current is used mainly in small or lightly powered cicuits. The components are cheaper to produce that run on DC The main problem with DC is that if any great distances have to be covered by the cicuits (miles) then there is a great loss of power. This is not a factor in an automobile but to run all the housing and factories in the country and distribute power everywhere DC is unsuitable. On the other hand AC current is just the job. It will travel well over long distances it is easier to use transformers to boost power, and is in fact used in households and factories all over the country. For use in automobiles it's main problem is it very difficult to store (batteries do not produce or store AC and power is required to start the engine. AC could only be produced when the engine was running. The final thing is that a battery (DC) ensures a fairly stable VOLTAGE a must with electronic components. (Yes computors run on DC they have a internal transformer to change from AC to DC).

HERTZ is the measurement of the fequency of a cycle. Every time the AC current changes direction and goes back again is one cycle. If the cycle repeats 120 times a second then it is 120 hz.

A Digital Mulimeter will measure Volts, Ohms and Amps though there is a limit with the Amps. An Oscilloscope will measure Hertz and Volts