Chevrolet TrailBlazer, Service Manual, Page: 342 / 677

trait of lower resistance with higher temperatures (negative temperature
coefficient). These principles are used in many of the sensors on the engine.
Ohm's Law
There is a direct relationship between current, voltage and resistance. The relationship
between current, voltage and resistance can be summed up by a statement known as
Ohm's law.
Voltage (E) is equal to amperage (I) time’s resistance (R): E=I x R
Other forms of the formula are R=E/I and I=E/R
In each of these formulas, E is the voltage in volts, I is the current in amps and R is the
resistance in ohms. The basic point to remember is that as the resistance of a circuit goes
up, the amount of current that flows in the circuit will go down, if voltage remains the same.
The amount of work that the electricity can perform is expressed as power. The unit of
power is the watt (w). The relationship between power, voltage and current is expressed
as:
Power (w) is equal to amperage (I) time’s voltage (E): W=I x E
This is only true for direct current (DC) circuits; the alternating current formula is a tad
different, but since the electrical circuits in most vehicles are DC type, we need not get into
AC circuit theory.