Resistors are usually very tiny and it is difficult to print resistance values on them. So color bands are printed on them that represent the electrical resistance they carry. These color bands are known as resistor color code.
Resistor Color Code
To read them, hold the resistor such that the tolerance band is on your right. The tolerance band is usually gold or silver in color and is placed a little further away from the other bands.
Starting from your left note all the colors of the bands and write them down in sequence. Next, use the table given below to see which digits they represent. The band just next to the tolerance band is the multiplier band. So if the color of this band is Red (representing 2), the value given is 102.
Here’s an example to get you started:
The band colours for resistor color code in order are:
|Band colours in order||RED||RED||BLACK||GOLD|
So the value of resistance is: 2 2 × 101 ± 5% = 220 ± 11 Ω
The tolerance values represent by how much the resistance can vary from its mean value in terms of the percentage. A gold band represents the lowest variation, so be sure to buy these that the electronics store.
Note that the band next to the tolerance band represents the multiplier. All bands left of this band give the digits. There can be more than two such bands. For example,
|Band colours in order||RED||BLACK||GREEN||ORANGE||YELLOW||SILVER|
Value is 2153× 104 ± 10% = 21.53 M Ω ± 2153 k Ω
You can remember the number values using this mnemonic:
BB ROY of Great Britain had a Very Good Wife. The Capital letters represent the first letters of the colours and their positions the digit values.
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Meanwhile, watch an interesting video on Electricity and Resistance.