Many cells in the body have a cell membrane whose inner and outer surfaces carry opposite charges, just like the plates of a parallel-plate capacitor. Suppose a typical cell membrane has a thickness of 8.1 × 10-9 m, and its inner and outer surfaces carry charge densities of -0.58 × 10-3 C/m2 and +0.58 × 10-3 C/m2, respectively. In addition, assume that the material in the cell membrane has a dielectric constant of 5.5.

(a) Find the direction and magnitude of the electric field within the cell membrane.

(b) Calculate the potential difference between the inner and outer walls of the membrane, and indicate which wall of the membrane has the higher potential.