The compensation theorem is particularly useful for the following purposes :
(i) To calculate the sensitivity of a bridge network.
(ii) To analyse those networks where the values of the branch elements are varied and for studying the effect of tolerance on such values.
This theorem is stated as follows :
“If a change, say ΔR, is made in the resistance of any branch of a network when the current was originally I, then the change of current at any other point in the network may be calculated by assuming that an e.m.f -I ΔR has been introduced into the changed branch while all other sources have their e.m.f s. suppressed and are represented by their internal resistances only”.