  We study the N/Z and N/A dependence of balance energy (E$_{bal}$) for
isotopic series of Ca having N/Z (N/A) varying from 1.0 to 2.0 (0.5 to 0.67).
We show that the N/Z (N/A) dependence of E$_{bal}$ is sensitive to symmetry
energy and its density dependence at densities higher than saturation density
and is insensitive towards the isospin dependence of nucleon-nucleon (nn) cross
section and Coulomb repulsion. We also study the effect of momentum dependent
interactions (MDI) on the N/Z (N/A) dependence of E$_{bal}$. We find that
although MDI influences the E$_{bal}$ drastically, the N/Z (N/A) dependence of
E$_{bal}$ remains unchanged on inclusion of MDI.
