Our goal in this post is to discuss Using Ohms law and the Power Formula. First, there are some terms that need defining. When a path is created for electrical current to flow a circuit is created. A Circuit Diagram (schematic) is shown below using schematic symbols.
Volt [ V ], Ampere [ A ] and Ohm [ Ω ]
Electrical Current is represented by the letter “I” which stands for Intensity of current. Voltage is represented by the letter “E” for electromotive force. And, “R” standing for resistance. The relationship between these three quantities is known as Ohm’s Law. Using the equation below allows you to calculate any third value if the other two values are known.
“Power” is another quantity that is extremely important to define. Power is the product of current and voltage. (P=IxE) Heat is produced as current flows through resistance. The “watt” is the unit of measure for power. The Ohms law triangle works by covering up the quantity you are looking for to find out how to calculate that quantity. The Power Wheel shown below works the same way. An expanded version is also shown with formulas for all four quantities.
Most quantity values in electronics are either very large or small. Power values might range from .ooooo1 Watt or less to 1000000 Watts or more. Multiple zeros can be a problem. Scientific Notation is used to reduce the chances of error when dealing with such large and small values. 4kW;5M ohms;20mA;60uV are examples of quantities expressed in scientific notation. Learning how to use scientific notation in math will make calculations much easier.
More terminology definitions and information regarding resistors will be the subject of the next post.
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