How to calculate resistor resistance using color code? Why resistors need to be colored? Resistor calculator method comes so far because resistor is too tiny to define the value on its body like other components capacitors, inductor etc. It is very difficult to make resistors with fixed value. It depends upon temperature. For changing value with the temperature tolerance is used. Using tolerance we can get accurate value of resistors. Tolerance is denoted with percentage terms. For example if resistor’s value is 1000Ω with ±5% tolerance. It means resistor values can be changed to 50Ω. Minimum value 950Ω and maximum 1050Ω.Meaning of ±5% tolerance is that its value within 950Ω to 1000Ω based on temperature
Resistors are used different types of electrical and electronics machine hugely. For the purpose of making little types of machine resistors, resistors are made small. So, it is impossible to write the values on resistors body. Every resistor has a value. To indicate it different types of color is used on resistors. This is called color is used on resistors. This is called color code of resistance.
Resistor Color Code Calculation Theory
Figure: Resistor Color Code Chart
Figure: Block Diagram of Resistor Band
There is a easy way to remember resistor color code. Memorize the sentence “B.B ROY Good Boy Very Good Worker”. Look at Capital letters first letter. Zero to nine is sequentially arranged in numbers. First letter B indicates Black and its value is 0. W indicates white and value 9. Every resistor has some color band of its body. First two color bands indicate resistors first mathematical term. Third color band multiply with first and second. Fourth band indicates tolerance. If fourth color band is absent then its tolerance is ±20%.
Follow the law Resistors resistance = FS *10^T± Tolerance
F= first color bands value
S= second color bands value
T= third color bands value.
For example suppose
F = yellow = 4
S = violet = 7
T = orange = 3
Tolerance = ±3%
R = FS*10^T±Tolerance
= 47*103 ±3%
=47 k ±3%
= 1.41 k
Maximum value = (47+1.41) k = 48.41 k
Minimum value = (47-1.41) k = 45.59 k