  A well known result for the interference of two single-mode fields is that
the degree of coherence and the degree of indistinguishablity are same when we
consider the detection of a single photon. In this article we present the
relation between degree of coherence, path indistinguishability and the fringe
visibility considering interference of multiple number of single-mode fields
while being interested in the detection of a single photon only . We will also
mention how Born's rule of interference for multiple sources is reflected in
these results.
