The Voltage Over a Sample

By inserting for the chemical potentials of ions and by using % = 1 we obtain from Eq. (1.19)  

We now integrate the electrical potential gradient over the thickness of the sample, from Side I to Side II, in order to obtain the voltage, U, over the sample  

We further assume that the voltage is measured using the same inert metal on both sides, for example, platinum. This eliminates the difference between chemical potentials of electrons on the two sides, and the voltage measured between the 

---