Some cell walls in the human body have a layer of negative charge on the inside surface and a layer of positive charge of equal magnitude on the outside surface. Suppose that the charge density on either surface is ± 0.50 × 10^-3 C/m², the cell wall is 5.0 nm thick, and the cell-wall material is air.

(a) Find the magnitude of E̅(vector) in the wall between the two layers of charge. 

(b) Find the potential difference between the inside and the outside of the cell. Which is at the higher potential?

(c) A typical cell in the human body has a volume of 10^-16 m³. Estimate the total electric-field energy stored in the wall of a cell of this size. (Hint: Assume that the cell is spherical, and calculate the volume of the cell wall.)

(d) In reality, the cell wall is made up, not of air, but of tissue with a dielectric constant of 5.4. Repeat parts (a) and (b) in this case.