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A model of a red blood cell portrays the cell as a spherical capacitor, a positively...

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 1.20 ✕ 10−12 kg, estimate the volume of the cell and thus find its surface area. The density of blood is 1,100 kg/m3. (Assume the volume of blood due to components other than red blood cells is negligible.)

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 charges does the surface charge represent?

___________

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