ELECTRICAL SYSTEM
3
Basics of electricity
In order to diagnosis any electrical system there are
few things the technician must understand:
• Basic electrical values: voltage, current and
resistance
•Ohm’s law.
• Kirchhoff’s current law.
• Kirchhoff’s voltage law.
• How the system is wired together.
The first electrical value to be discussed is Voltage.
• Voltage is the “pressure” that electricity has. It is
the amount of force pushing electrons through a
circuit.
• This pressure is measured in volts.
• The capital letter “V” is used to represent volts.
The second electrical value is Current:
• Current is the “flow” of electricity. It is the amount
of electrons flowing in circuit.
• The flow of current is measured in Amperes or
Amps for short.
• The capital letter “I” is used to represent Amps.
The third and final value is Resistance:
• Resistance is the opposition to current flow. It is
a restriction that slows down the flow of current.
• Resistance is measured in Ohm’s.
• The greek letter omega “Ω” or the capital letter
“R” is used to represent Ohm’s.
Ohm’s law
Ohm’s law state that voltage is the product of resis-
tance times current. It is written as V=IxR. An example
of how ohm’s law works goes like this: It takes 1 volt to
push 1 amp through a resistance of 1 ohm (1=1x1).
Ohm’s law can be drawn in a triangle. When using the
triangle, cover the value to be found, and the two val
-
ues left exposed signify how to obtain that value.
See Figure 2.1.
As an example if the “R” is covered, the “V” is over the
“I” which means V is divided by I. If the “V” is covered,
“I” and “R” is exposed, meaning IxR and so on.
Figure 2.1
V
I
R
CHAPTER 2: ELECTRICAL SYSTEM
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