The colour code of Resistor

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THE  COLOUR  CODE  :-



          The resistance value of many resistors can  be  determined  by reading  a  series  of colour   band   printed  on   the  resistor   as shown  in   above   figure.  The   scheme   of finding the resistance value is called colour code.
 
     

       The first three bands of the colour code are used  specify the  resistance  value  and the fourth band is to  specify the  tolerance.
For easy understanding of this colour code concept by using a sentence as shown below.


B.B. ROY of Great Britain has a Very Good Wife

The capital letters of each word indicatescolour as shown below .

Consider an example we can find the digits  are  1  and  0   respectively.   Therefore   the numerical    value   of the resistor is 10.  The third band tells us the power of 10 by which the first two digits are multiplied. Since the third band is orange and the corresponding digit is 3,  we multiply   10 with  10^3 which gives us a value of 10k ohms .

For example , a resistor is marked
1st  band Grey
2nd  band  Red
3rd band  Green
4th  band no colour
What is the resistance value  ??

Solution:-                                                             
From the above table

Colour               Digit
Grey                     8
Red                       2
Yellow                  5
No colour           20 %  tolerance

So,
The resistor value =82×10^5 (+/-) 20%
                                  =8.2×10^6 (+/-)20%
                                  =8.2M ohms(+/-)20%

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