  The decay of photon by the influence of magnetic field is considered. It is
shown here that if the photon energy is grater than 1 MeV then photon can decay
electron positron pair, but if it remains below 1 MeV then photon decays into
neutrino antineutrino pair. The decay rates for both of the processes are
calculated. All possible Feynman diagrams are taken into account to construct
the matrix element for either of the processes. In the second process all three
type of neutrinos are considered. The significance of these processes are
discussed briefly.
