To know the value of resistance colour code is used. These code are printed in form of set of rings or strips. By reading the values of colour bands, we can estimate the value of resistance.
The carbon resistance has normally four coloured rings or bands say A, B, C and D as shown in following
figure.
Decimal values of color bands are shown in the table.
`text(Colour band A and B :)`Indicate the first two digit of resistance in ohm.
`text(Band C :)`Indicates the decimal multiplier i.e. the number of zeros that follows the two significant figures A and B.
`text(Band D :)` Indicates the tolerance in percent about the indicated value or in other words it represents the
percentage accuracy of the indicated value.
The tolerance in the case of gold is - 5% and in silver is - 10%. If only three bands are marked on
carbon resistance, then it indicate a tolerance of 20%.