A.c. Josephson effect

Ideally a standard cell is constmcted simply and is characterized by a high constancy of emf, a low temperature coefficient of emf, and an emf close to one volt. The Weston cell, which uses a standard cadmium sulfate electrolyte and electrodes of cadmium amalgam and a paste of mercury and mercurous sulfate, essentially meets these conditions. The voltage of the cell is 1.0183 V at 20°C. The a-c Josephson effect, which relates the frequency of a superconducting oscillator to the potential difference between two superconducting components, is used by NIST to maintain the unit of emf. The definition of the volt, however, remains as the Q/A derivation described. 

Acid yellow (Aquashade), herbicide/algicide for aquaculture in U.S., 3 214t Acitretin, 25 790 a-c Josephson effect, 15 750 Aclame, 24 232 ac losses, 23 845-846 Acne, vitamin A treatments for, 25 789 cis-Aconitic acid, in citric acid cycle, 6 633 Aconitine, 2 103... 

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