The Resistor Colour Code
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The code is a convenient way to tell the resistance of a resistor.
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It is also used for other components such as capacitors
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Coloured bands are placed on a resistor. Each band has a numerical value.
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Bands are read from left to right.
1 - First colour band = 1st digit
2 - Second colour Band = 2nd digit
3 - Third colour Band = Multiplier
The last band (usually separated from the others) = the tolerance (how accurate the R value is)
Resistors colour codes - The following table should be memorized
|
COLOUR OF BAND
|
FIRST BAND
|
SECOND BAND
|
Multiplier
|
Tolerance
|
|
BLACK
|
0
|
0
|
1
|
|
|
BROWN
|
1
|
1
|
10
|
|
|
RED
|
2
|
2
|
100
|
|
|
ORANGE
|
3
|
3
|
1,000
|
|
|
YELLOW
|
4
|
4
|
10,000
|
|
|
GREEN
|
5
|
5
|
100,000
|
|
|
BLUE
|
6
|
6
|
1,000,000
|
|
|
VIOLET
|
7
|
7
|
10,000,000
|
|
|
GRAY
|
8
|
8
|
100,000,000
|
|
|
WHITE
|
9
|
9
|
1,000,000,000
|
|
|
SILVER
|
|
|
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+ or - 10%
|
|
GOLD
|
|
|
|
+ or - 5%
|
EXAMPLE: What is the value of resistance of a resistor with the following coloured bands:
Yellow, green, red, gold
Yellow, green, red, gold
Solution
Yellow = 4 à first number = 4
Green = 5 à second number = 5
Red (in the third band) = X100
Therefore: THE VALUE OF THE RESISTOR IS 45x100 = 4,500 ohms OR 4.5kΩ (4.5 KILO-OHMS)
Yellow = 4 à first number = 4
Green = 5 à second number = 5
Red (in the third band) = X100
Therefore: THE VALUE OF THE RESISTOR IS 45x100 = 4,500 ohms OR 4.5kΩ (4.5 KILO-OHMS)
Since the last band is gold, the accuracy of this resistor is ± 5%.
This means that it can have a value that can go from a high value of [4500 + 5%*(4500)] = [4500 + 225] = 4725 Ω to a low value of ..... [4500 – 5%*(4500) ] = [4500 - 225] = 4275 Ω
