• DOI:10.1119/1.4826445
• Corpus ID: 119278961

The Daniell cell, Ohm's law, and the emergence of the International System of Units

@article{Jayson2014TheDC,
  title={The Daniell cell, Ohm's law, and the emergence of the International System of Units},
  author={Joel S. Jayson},
  journal={American Journal of Physics},
  year={2014},
  volume={82},
  pages={60-65}
}

• J. S. Jayson
• Published 22 December 2015
• Education
• American Journal of Physics

Telegraphy originated in the 1830s and 40 s and flourished in the following decades but with a patchwork of electrical standards. Electromotive force was for the most part measured in units of the predominant Daniell cell, but each telegraphy company had their own resistance standard. In 1862, the British Association for the Advancement of Science formed a committee to address this situation. By 1873, they had given definition to the electromagnetic system of units (emu) and defined the practical units of the ohm as 109 emu units of resistance and the volt as 108 emu units of electromotive force. These recommendations were ratified and expanded upon in a series of international congresses held between 1881 and 1904. A proposal by Giovanni Giorgi in 1901 took advantage of a coincidence between the conversion of the units of energy in the emu system (the erg) and in the practical system (the Joule). As it was, the same conversion factor existed between the cgs based emu system and a theretofore undefined MK...