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A Kibble balance is a metrological instrument that measures the weight of a test object by the electric current and voltage needed to produce a compensating force. It can realize the definition of the kilogram based on fundamental constants and was used to redefine the SI unit of mass in 2019.
The current to be measured is passed in series through two coils of wire, one of which is attached to one arm of a sensitive balance. The magnetic force between the two coils is measured by the amount of weight needed on the other arm of the balance to keep it in equilibrium. This is used to calculate the numerical value of the current.
Two current-carrying wires attract each other magnetically: The bottom wire has current I 1, which creates magnetic field B 1. The top wire carries a current I 2 through the magnetic field B 1, so (by the Lorentz force) the wire experiences a force F 12. (Not shown is the simultaneous process where the top wire makes a magnetic field which ...
Learn how James Clerk Maxwell unified electromagnetism and light in the 19th century, and how his equations were derived, modified, and verified by other scientists. Explore the experimental and theoretical background, the mechanical models, and the vector formulation of Maxwell's equations.
In the experiment the working electrode is held at a constant potential and current is monitored over time . In a properly run experiment an analyte is quantitatively converted from its original oxidation state to a new oxidation state, either reduced or oxidized. As the substrate is consumed, the current also decreases, approaching zero when ...
Coulomb's law is an experimental law of physics that calculates the amount of force between two electrically charged particles at rest. It states that the force is proportional to the product of the charges and inversely proportional to the square of the distance between them.
Now generally referred to as the Eötvös balance, this device is commonly used today in prospecting by searching for local mass concentrations. Using the new device a series of experiments taking 4000 hours was carried out with Dezsö Pekár (1873–1953) and Jenő Fekete (1880–1943) starting in 1906.
The Cavendish experiment measured the force of gravity between masses using a torsion balance, a device that consists of a horizontal rod suspended by a wire. The experiment was performed by Henry Cavendish in 1797-1798 and yielded accurate values for the gravitational constant and the Earth's density.