The Resistor
Here I begin with the most common component that you might have heard before-its the resistor.
A resistor is a component that restricts or opposes the electrical current in the circuit it occupies. This is done through the chemicals that make up the resistor(carbon). The is used to control the electrical current with the voltage in order to create stable current. Resistance is calculated when the voltage (measured in volts) is devided by the current (measured in amperes). The unit for resistance is "Ohms". The diagram below will help you with the ohms law formula.
If you want to remember how to
calculate resistance, just cover the "R" in the diagram
and it will give you the formula. By covering it you will find
that resistance R= V/I
The same goes for the voltage and the current. Try it and see how it works! (Please note that the "X" represents mulitplication)
Now that we have a little basic understanding of what a resistor is and how to calculate its resistance it now time for a little more advance stuff. The resistor has these little colored bands that tells you the resistance of that particular resistor. This is good for both the manufacturers and the technicans when providing and using these components. Each color band represents a specific value in the calculation of the resistor's ohmic value.
| Color of Rings | 1 st Color Ring # value | 2 nd Color Ring # value | 3 rd Color Ring # mulitplier | 4 th Color Tolerance |
| Black | 0 | 0 | x 1 | |
| Brown | 1 | 1 | x 10 | + or - 1% |
| Red | 2 | 2 | x 10^2 | + or - 2% |
| Orange | 3 | 3 | x 10^3 | |
| Yellow | 4 | 4 | x 10^4 | |
| Green | 5 | 5 | x 10^5 | |
| Blue | 6 | 6 | x 10^6 | |
| Violet | 7 | 7 | x 10^7 | |
| Grey | 8 | 8 | x 10^8 | |
| Gold | x 10^ -1 | + or - 5% | ||
| Silver | x 10^ -2 | + or - 10% | ||
| No Color | + or - 20% |
Here is an example of how the table works. A resistor consisting of the color bands Red, Red, Brown and gold have to be evaluated for its ohmic value.
Red = 2, Red = 2, Brown = x 10
The ohmic value in ohms R = 22 x 10 or 220 ohms
For the third color you have to find 5% of 220 which is a value of 11 ohms. This means that the value of this resistor can vary between the values (220 - 11) ohms and (220 + 11) ohms.
