Resistor Colour Coding and Ohmic Values

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(a) Colour code for fixed resistors

The colour code for fixed resistors is given in table.

Colour

Significant Figures

Multiplier

Tolerance

Silver 10-2 ±10%
Gold 10-1 ±5%
Black 0 1
Brown 1 10 ±1%
Red 2 102 ±2%
Orange 3 103
Yellow 4 104
Green 5 105 ±0.5%
Blue 6 106 ±0.25%
Violet 7 107 ±0.1%
Grey 8 108
White 9 109
None ±20%

For a four-band fixed resistor (i.e. resistance values with two significant figures): yellow-violet-orange-red indicates 47 kΩ with a tolerance of ±2%

(Note that the first band is the one nearest the end of the resistor)

For a five-band fixed resistor (resistance values with three significant figures): red-yellow-white-orange-brown indicates 249 kΩ with a tolerance of ±1%

(Note that the fifth band is 1.5 to 2 times wider than the other bands)

(b) Letter and digit code for resistors

Another way of indicating the value of resistors is the letter and digit code shown in Table.

Resistance Value

Marked as:

0.47 Ω R47
1 Ω 1R0
4.7 Ω 4R7
47 Ω 47R
100 Ω 100R
1 kΩ 1 K0
10 kΩ 10 K
10 MΩ 10 M

Tolerance is indicated as follows: F = ±1%, G = ±2%, J = ±5%, K = ±10% and M = ±20%
Thus, for example,

R33M = 0.33 Ω ± 20%
4R7K = 4.7 Ω ± 10%
390RJ = 390 Ω ± 5%

Read More Topics
Electric current and quantity of electricity
Standard symbols for electrical components
Electrical / electronic system block diagram
Power and signal transmission

Santhakumar Raja

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