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Basic Electricity:
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Electricity is the flow of electrons through a medium.
Media through which electrons flow easily are called,
"conductors;" Those through which the flow is difficult
are called, "insulators." The metal core of an electrical
wire is a conductor. The rubber or plastic that surrounds
it, keeping the metal from touching other wires (or you),
is an insulator.
The degree to which a conductor allows or does not allow
the flow of electrons is its "resistance". It is measured in ohms
(named after
Georg Simon Ohm).
The pressure which causes electrons to flow throw a conductor
is called "electromotive force," or voltage, and is measured in
volts (for
Alessandro Volta, who invented what some regard as
the first electric battery).
The speed with which the electrons flow is called "current," and
is measured in amperes or "amps" (for
André-Marie Ampère, the father
of electrodynamics).
The amount of electrical "work" that gets done is called "power,"
and is measured in watts (named after
James Watt, whose invention
of the first practical steam engine brought on the Industrial
Revolution).
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Ohm's Law:
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A description
of the relationship between voltage, current, and resistance, where:
- E stands for voltage
(or "electromotive force")
- I stands for current (from the French word, "intensite"), and
- R stands for resistance.
Ohm's Law is expressed thusly:
E = IR
So, if we know that our voltage is 120V and our current is 20A,
we can calculate the resistance:
120 = 20xR
120/20 = 6
Therefore, our resistance is 6 ohms. Since the mathematical symbol
for "ohm" is the Greek letter Omega, we write this answer as:
6Ω
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The Power Equation:
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Describes the relationship between wattage, current, and voltage, where:
- E stands for voltage
(or "electromotive force")
- I stands for current, and
- P stands for wattage (or "power")
Because of these symbols, the Power Equation is often referred to
as the "PIE" formula:
P=IE
If, as in the above example, our voltage is 120V and our current is
20A, we can use the Power Equation to calculate the wattage:
P = 20 x 120
20 x 120 = 2400
...So our power is 2400W.
If, however, our voltage is 240V and our current is
10A, the equation looks like this:
P = 10 x 240
10 x 240 = 2400
...So our power is still 2400W.
The Power Equation is also known as the "West Virginia" formula,
because it can also be expressed with these symbols:
W=VA
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