H            Electric Potential Energy
                                 and Electric Potential
  Electric Potential Energy (Joules)

Capacitors exist everywhere. Nature has evolved nerve cells of which the axons are capacitors of a sort!
By creating a capacitor (cell membrane) and an Electric Field between the surfaces of the cell membrane we are able to store energy in the Electric Field for later use. We transform the energy in the Electric field to energy of motion.

Electric Potential Energy (U = EPE)

Work required to move a charge in an Electric Field
For the axon (nerve cell) to propagate an electrical signal, it must store energy. That stored energy is in the form of an Electric Field. The cell membrane is a capacitor. The Electric Field is created from the concentration of ions inside and outside the cell membrane. Now, all the cell has to do is allow the concentrations to change. This requires work.

Distance (meters)

W is Electric Potential Energy (Joules)
is not
V is Electric Potential (Joules/Coulomb)
a.k.a Voltage, Potential Difference

Equipotential Surfaces

No work is required for a charge to move along an equipotential surface.
Work is required for a charge to move to a different equipotential surface.

Summary of Equations

Capacitors I, II, III

The Electric Field
The Electric Force

Problem Solving

Conservation of Energy
The Mechanical Universe
Physics 196
The Action Potential




In chapter 18, I like these medium problems

14, 26, 34, 63, 69, 76, 81

and any basic problems