Chapter 26, Problem 62MSPP

Cell Membrane Resistance

The capacitance of biological membranes is about 1.0 μF per cm² of membrane area, so investigators can determine the surface area of a cell membrane by using intracellular electrodes to measure the membrane’s capacitive reactance. An investigator applies a 1.0 μA peak current at 40 kHz to a cell and measures the peak out-of-phase voltage—that is, the component of the voltage due to the capacitive reactance of the cell membrane—to be 0.16 V.

If the frequency is doubled to 80 kHz and the current is kept the same, what will be the peak out-of-phase voltage?

A. 0.32 V

B. 0.16 V

C. 0.080 V

D. 0.040 V