RESISTOR VALUES AND MARKINGS

The unit of measure for resistance is the ohm, which is represented by the Greek letter W. Before technology improved the process of manufacturing resistors, they were first made and then sorted. By sorting the values into groups that represented a 5% change in value, (resistor values are 10% apart), certain preferred values became the standard for the electronics industry. Table  shows the standard values for 5% resistors.

Resistors are marked by using different colored rings around their body. The first ring represents the first digit of the resistor’s value. The second ring represents the second digit of the resistor’s value. The third ring tells you the power of ten to multiply by. The final and fourth ring represents the tolerance. For example, gold is for 5% resistors and silver for 10% resistors. This means the value of the resistor is guaranteed to be within 5% or 10% of the value marked. The colors in Table 2 are used to represent the numbers from 0 to 9.