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Basics of Electricity
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Figure 1.6. Electric voltage causes current to flow.
When water flows in the pipe, its flow is impeded by the size of the pipe and the work
performed, such as turning a lawn sprinkler. Similarly, current flowing in a conductor is impeded
by the size of the conductor and the work performed, such as turning the shaft of a connected
motor. Anything that impedes or resists current flow in a conductor is called electrical
resistance. See
Figure 1.7.
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Electrical resistance is identified
by capital letter . R. .
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Electrical resistance is measured
in ohms with an ohmmeter. The symbol for ohms is the Greek letter omega (W).
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Figure 1.7. Electrical resistance (R) impedes current flow.
Ohm's Law
To review, there are three characteristics of electricity:
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current (IIII) measured in amps
(A),
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voltage (E) measured in volts
(V),
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and resistance (R R) measured in
ohms (W).
THE THREE FACTORS ARE ALWAYS IN BALANCE AS DEFINED BY OHM'S LAW: VOLTAGE (E) EQUALS CURRENT
(IIII) TIMES RESISTANCE (R);
E = I x R.
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