Resistor Colour Code Guide ![]() Introduction The coloured bands around a resistor tell us its resistance value (measured in Ohms) and also how accurate this value is. In this section we will discover how the coloured bands do this. |
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Normally there are four coloured bands around a resistor. The first three bands tell us the resistor's value and the fourth how accurate this value is. Each colour represents a number as shown in the table to the right. 1, Working out the resistor's value: We start with the first two bands: These represent the first two numbers of the resistance value: In the example above: blue = 6 and grey = 8. So we begin by writing 68. The third band is known as the "multiplier" band, and this colour tells us how many zeros to write after the first two numbers. For this resistor, it is red, which represents 2. So we now write 00 after the first two numbers (6800). So the resistor's value = 6800 Ohms. or 6.8K Ohms (as 1K = 1000) |
When writing resistance values: 1,000 Ohms = 1 K Ohms 1,000,000 Ohms = 1 M Ohms |
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2, Working out the resistor's accuracy: Due to the materials and methods used to make resistors, actual values may be slightly different from the stated values. The fourth band tells us how accurate the stated value is. The margin of error (tolerance) is shown as a percentage. It could be a higher or lower amount. In our example the fourth band is gold, so the error could be plus or minus 5%. For our example resistor: the resistance value = 6.8 K Ohms +/- 5%. (If we could tolerate a bigger error, then a silver band with +/- 10% tolerance would be acceptable). ![]()
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