Two uniformly charged solid spheres are such that `E_1` is electric field at surface of `1^(st)` sphere due to itself. `E_2` is electric field at surface of `2^(nd)` sphere due to itself. `r_1, r_2` are radius of `1^(st)` and `2^(nd)` sphere respectively. If `E_1/E_2=r_1/r_2` then ratio of potential at the surface of spheres `1^(st)` and `2^(nd)` due to their self charges is :