Contact tension

Contact tension (also known as the contact electromotive force) is a force suggested by Alessandro Volta in 1800 to explain how electricity is generated in an electric battery or, as it was then called, the Voltaic pile. The validity of this model versus one based upon chemical reactions was debated for much of the 19th century in what has been called the Galvani-Volta controversy. While it was not the appropriate explanation for batteries, this model (which is now called the contact or Volta potential) is valid science. It plays an important role in contact electrification as well as in many areas of semiconductor physics such as p–n junctions. This only became apparent much later after a more complete understanding of phenomena such as work functions evolved based upon quantum mechanics.