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Bipolar electrochemistry scheme. In electrochemistry, standard electrode potential, or , is a measure of the reducing power of any element or compound.The IUPAC "Gold Book" defines it as; "the value of the standard emf (electromotive force) of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode".
The electrochemical cell voltage is also referred to as electromotive force or emf. A cell diagram can be used to trace the path of the electrons in the electrochemical cell. For example, here is a cell diagram of a Daniell cell: Zn(s) | Zn 2+ (1 M) || Cu 2+ (1 M) | Cu(s) First, the reduced form of the metal to be oxidized at the anode (Zn) is ...
Therefore, emf is expressed as = (+) where is emf and v is the unit charge velocity. In a macroscopic view, for charges on a segment of the loop, v consists of two components in average; one is the velocity of the charge along the segment v t , and the other is the velocity of the segment v l (the loop is deformed or moved).
In the theory of symbiogenesis, a merger of an archaean and an aerobic bacterium created the eukaryotes, with aerobic mitochondria, some 2.2 billion years ago. A second merger, 1.6 billion years ago, added chloroplasts, creating the green plants. [31] Eukaryotic cells were created some 2.2 billion years ago in a process called eukaryogenesis.
Both a 1 volt emf and a 1 volt potential difference correspond to 1 joule per coulomb of charge. In the case of an open circuit, the electric charge that has been separated by the mechanism generating the emf creates an electric field opposing the separation mechanism.
[2] Electromagnetic induction was discovered by Michael Faraday, published in 1831. [3] [4] It was discovered independently by Joseph Henry in 1832. [5] [6] In Faraday's first experimental demonstration, on August 29, 1831, [7] he wrapped two wires around opposite sides of an iron ring or "torus" (an arrangement similar to a modern toroidal ...
The electric potential at any location, r, in a system of point charges is equal to the sum of the individual electric potentials due to every point charge in the system. This fact simplifies calculations significantly, because addition of potential (scalar) fields is much easier than addition of the electric (vector) fields.
That is, the back-EMF is also due to inductance and Faraday's law, but occurs even when the motor current is not changing, and arises from the geometric considerations of an armature spinning in a magnetic field. This voltage is in series with and opposes the original applied voltage and is called "back-electromotive force" (by Lenz's law).