  The effect of low magnetic fields on the magnetic and electrical transport
properties of polycrystalline samples of the phase separated compound
La$_{0.5}$Ca$_{0.5}$MnO$_{3}$ is studied. The results are interpreted in the
framework of the field induced ferromagnetic fraction enlargement mechanism. A
fraction expansion coefficient af, which relates the ferromagnetic fraction f
with the applied field H, was obtained. A phenomenological model to understand
the enlargement mechanism is worked out.
