![]() The direction of conventional current (I) in a metallic path (conductor) is the direction of positively charged particles going from an electropositive potential to an electronegative potential (Figure 2). There are no electrons in the electrolyte electricity transfer through an electrolyte is due to a charge transfer of positively charged ions (cations) moving away from the anode and toward the cathode, while negatively charged ions (anions) move away from the cathode and toward the anode. Electricity in the electrolyte is due to the movement of ions (Figure 1).Įlectricity transfer through the metallic conductor is due to the movement of negatively charged electrons. An ion is an atom that has either more electrons than protons and is negatively charged, or has more protons than electrons and is positively charged. An atom consists of neutrons (neutral charge), protons (positive charge), and electrons (negative charge). 2 The electrolyte consists of molecules made up of atoms. Conventional Current or Electron DirectionĪn electrochemical cell (corrosion cell) consists of an anode and a cathode in an electrolyte connected by a metallic path (conductor) (Figure 1). Kuhn installed the first rectifier to impress current onto a pipeline in New Orleans, Louisiana, and established the first practical application of CP on pipelines that eventually spawned the formation of the National Association of Corrosion Engineers (now known as NACE International) in 1943.Īlthough CP is a well-recognized means of corrosion control and the basics are broadly understood, use of the terms “conventional current” and “electrons” can be confused. Geppert installed the first CP system on a pipeline in Germany in 1906, it never became popular in that country. ![]() Cohen achieved practical CP using impressed current. ![]() In 1831, Michael Faraday invented the electric dynamo (a crude power generator) to provide a practical means of generating a continuous supply of electricity.ĬP can be defined as a technique for reducing the corrosion of a metal surface by turning that surface into the cathode of an electrochemical cell. In 1812, Sir Humphrey Davy hypothesized that chemical and electrical charges are identical and discovered cathodic protection (CP) of copper using zinc or iron anodes. Alessandro Volta discovered that certain chemical reactions would produce electricity and in 1800, he constructed the voltaic pile-an electric battery that produced a steady electric current. Investigations into galvanic electricity and electrolytes were completed on frog legs in 1789 by Galvani. By the sixteenth century, many electrostatic discoveries were made, including an electrostatic generator.īenjamin Franklin’s famous kite flying, which generated a spark from a key during an electrical storm in 1752, proved that lightning was a large electrical spark (arc). In 1600, William Gilbert used the Latin word “ electricus” to describe the force that certain substances exert when rubbed against each other. In ancient Greece, it was likely that cloth fibers clung to the amber jewelry and attempts to rub them off proved futile due to static electricity. Amber is a resinous mineral use to make jewelry. The word electricity comes from “ elecktron,” the Greek name for amber. There is speculation that the silversmiths of Baghdad used these batteries in electroplating small articles. 1 The iron rod in the center of the copper sheet was cylindrical at the top and changed to a pencil shape at the bottom, which suggests a bimetallic corrosion cell and that batteries were invented in that era. Clay pots containing an iron rod surrounded by a copper sheet were found in relics from about 27 B.C to 395 A.D. The question as to who discovered electricity (and when) is open to question, but it appears to go back ~2,000 years. Electricity is a form of energy generated by friction, induction, or chemical change (electrochemistry), while current is a moving stream of charged particles, principally electrons.
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