Calculate the capacitance per unit length of an axon of radius 4.5 µm. The membrane acts as an insulator between the conducting fluids inside and outside the neuron. The membrane is 5.3 nm thick and has a dielectric constant of 7.0. (Note: The membrane is thin compared to the radius of the axon, so the axon can be treated as a parallel plate capacitor.)
What is the magnitude of the charge density on the surfaces of the membrane?