A model of a red blood cell portrays the cell as a spherical capacitor, a positively charged liquid sphere of surface area A separated from the surrounding negatively charged fluid by a membrane of thickness t. Tiny electrodes introduced into the interior of the cell show a potential difference of 100 mV across the membrane. The membrane's thickness is estimated to be 99 nm and has a dielectric constant of 5.00.
(a) If an average red blood cell has a mass of 1e-12 kg, estimate the volume of the cell and thus find its surface area. The density of blood is 1100 kg/m3. volume = m3 surface area = m2
(b) Estimate the capacitance of the cell by assuming the membrane surfaces act as parallel plates. F
(c) Calculate the charge on the surface of the membrane. C How many electronic (elementary) charges does the surface charge represent?