Voltage power and current, where 1 volt = 1 watt (of power) per 1 ampere (of current). This definition is equivalent to the more commonly used 'joules per coulomb'. Voltage or electric potential difference is denoted symbolically by , but more often simply as "V", for instance in the context of Ohm's or Kirchhoff's circuit laws. Electric potential differences between points can be caused by electric charge, by electric current through a magnetic field, by time-varying magnetic fields, or some combination of these three. A voltmeter can be used to measure the voltage (or potential difference) between two points in a
Transepithelial potential difference increased in cystic fibrosis, making it a potential diagnostic tool for this disorder. In the kidney, TEPD contributes to tubular reabsorption. Transepithelial potential difference Transepithelial potential difference (TEPD) is the voltage across an epithelium, and is the sum of the membrane potentials for the outer and inner cell membranes. The diagnosis of Cystic Fibrosis (CF) is usually based on high sweat chloride concentrations, characteristic clinical findings (including sinopulmonary infections), and/or family history. However, a small portion of patients with Cystic Fibrosis especially those with "mild" mutations of the Cystic Fibrosis Transmembrane Regulator ion channel (CFTR), have near-normal sweat tests. In