To identify value of resistance of a resistor colour coding is used. Because size of the resistor is very small so we cant print resistance value on the physical structure. Thus we use coloured rings, These coloured painted bands produce a system of identification generally known as a Resistors Colour Code. Generally there are four colour rings in the resistor, first and second ring indicates two digits of the resistance value. Third ring indicates multiplier which made the colour coding more flexible from fractions to millions. fourth and final ring indicates tolerance value, which means maximum change of the resistance value that may occurred, which dependence on the manufacturing process, tolerance ius represented in percentage. suppose fourth ring is in golden colour that means its tolerance value is ± 5%, this plus or minus sign indicates that it may change to and fro. so 5 % of the resistance may increase or decrease from the indicated value.
It is very difficult to memorize the colour codings in proper order. but It is easier to remember the resistor colour code by using mnemonics or phrases that have a separate word in the phrase to represent each of the Ten in the code. Here we are providing such kind of a sentrace, where each bolded letter represent different colours.
B B ROY of Great Britain has Very Good Wife.
Resistors are available in a range of different resistance values from fractions of an Ohm ( Ω ) to millions of Ohms. But it is very difficult to produce resistors for all numeric values, so a standardization is introduced, that is resistors are valuable for certain standard values