Suppose biological cell membrane has a specific capacitance of ~1μF/cm^2. Calculate the capacitance of a typical cell with diameter of ~10 μm. Suppose the membrane potential is -60mV, calculate the amount of net charge kept inside the cell. Calculate how many Na+ ions need to go across the membrane to alter the membrane potential from -60mV to 40 mV.
Note: The charge of a single Na+ ion = 1.602x 10^(-19) C
(Reference: https://www.scholarpedia.org/article/Electrical_properties_of_cell_membranes)