Resistor Colour Codes

Here's a memory aid to help you remember the way resistor values are represented by coloured bands on the resistor itself. There are other mnemonics, but this is the most complete, and the most polite one I’ve found. It's based on remembering this sentence:

     Black Beer Rots Our Young Guts But Vodka Goes Well – Get Some Now!
Write this down as the first column in a chart, then use the first letter of each word to remind you of the colours in the second column. From there, you can fill in the numbers in the 3rd column (remember to start at zero, and double the tolerances).

Memory   Band
 Aid    Colour  Value
------  ------- ------
Black   Black   zero
Beer    Brown    1
Rots    Red      2
Our     Orange   3
Young   Yellow   4
Guts    Green    5
But     Blue     6
Vodka   Violet   7
Goes    Grey     8
Well    White    9
- - - - - - - - - - -
Get     Gold     5%
Some    Silver   10%
Now     None     20%

Start at the end of resistor where the colour bands are nearest the end of the resistor. The first 2 colour bands tell you the first 2 digits of the resistance.
Remember that the 3rd number is the number of zeros to add after the number formed by the first 2 digits.

“105” does not represent “one hundred and five”, but is actually “10 followed by 5 zeros”, or 10 00 000 Ohms, or 1 MegaOhm

  Examples:

     yellow violet red          is   a 4700 Ohm  resistor with a  20% tolerance
     orange white yellow gold   is   a 390,000 Ohm resistor with a 5% tolerance

References

-For further details, have a look at page 2-9 in your study guide.
-more resistor information: - http://en.wikipedia.org/wiki/Resistor
-online resistor value calculators: - http://www.csgnetwork.com/resistcolcalc.html
- http://www.electronics2000.co.uk/calc/resistor-code-calculator.php#

5-band axial resistors

5-band identification is used for higher precision (lower tolerance) resistors (1%, 0.5%, 0.25%, 0.1%), to specify a third significant digit. The first three bands represent the significant digits, the fourth is the multiplier, and the fifth is the tolerance. Five-band resistors with a gold or silver 4th band are sometimes encountered, generally on older or specialized resistors. The 4th band is the tolerance and the 5th the temperature coefficient.