BASE 1691412 - Caterpillar

Introduction to Ohm's Law
In 1827 a mathematic reasoning to electronics called Ohm's Law was established by George Simon Ohm. Ohm's Law is a fundamental law of electricity, that relates the quantities of voltage, current, and resistance in a circuit.Basic Direct Current Circuit Elements
Illustration 1 g01070291
A circuit is a path for electric current. Current flows from one end of a circuit to the other end when the ends are connected to opposite charges. The ends are usually called power and ground. Current flows only in a closed circuit or a completed circuit. Current cannot flow if there is a break in the circuit. Every electrical circuit should contain the following components:
Power Source
Protection device (fuse or circuit breaker)
Load (light)
Control Device (switch)
GroundThese devices are connected together with conductors in order to form a complete electrical circuit.General Rules of Ohm's Law
Ohm's Law states that current flow in a circuit is directly proportional to circuit voltage and inversely proportional to circuit resistance.This means that the amount of current flow in a circuit depends on how much voltage or how much resistance there is in the circuit.Since most Caterpillar electrical circuits that are on mobile equipment use a 12 volt source or 24 Volt source, the amount of current will be determined by how much resistance is present in the circuit.Remember, current flow does the work. Voltage is only the pressure that moves the current. Resistance is opposition to the current flow.The rules that are needed to understand, predict, and calculate the behavior of electrical circuits are grouped under the title Ohm's Law. You can derive the following general rules from the Ohm's Law equation.Assuming the resistance does not change:
As voltage increases, current increases.
As voltage decreases, current decreases.Assuming the voltage does not change:
As resistance increases, current decreases.
As resistance decreases, current increases.Ohm's Law Equation
Ohm's Law can be expressed as the following algebraic equation:
E stands for electromotive force (voltage).
I stands for intensity (amperage).
R stands for resistance (ohm's).If you know two parts of the Ohm's Law equation, you can calculate the third part. For example:To determine voltage, multiply current times resistance.To determine current, divide voltage by resistance.To determine resistance, divide voltage by current.Ohm's Law Solving Circle
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The Ohm's Law solving circle is an easy way to remember how to solve any part of the equation. To use the solving circle (Illustration 2), cover any letter that you do not know. The remaining letters give you the equation for determining the unknown quantity. Voltage Unknown
Illustration 3 g01070300
In this circuit, the value of the source voltage is unknown. The resistance of the load is 2 ohms. The current flow through the circuit is 6 amps. Since the voltage