The membrane that surrounds a certain type of living cell has a surface area of 7.3 x 10-9 m2 and a thickness of 1.9 x 10-8 m. Assume that the membrane behaves like a parallel plate capacitor and has a dielectric constant of 4.3.
(a) The potential on the outer surface of the membrane is +50.9 mV greater than that on the inside surface. How much charge resides on the outer surface?
(b) If the charge in part (a) is due to K+ ions (charge +e), how many such ions are present on the outer surface?