|
William Thomson, Lord Kelvin
William Thomson, 1st Baron Kelvin (26 June 182417 December 1907), was a British mathematician, mathematical physicist and engineer. Born in Belfast, he was the professor of Natural Philosophy at the University of Glasgow for 53 years, where he undertook significant research on the mathematical analysis of electricity, was instrumental in the formulation of the first and second laws of thermodynamics, and contributed significantly to unifying physics, which was then in its infancy of development as an emerging academic discipline. He received the Royal Society's Copley Medal in 1883 and served as its president from 1890 to 1895. In 1892, he became the first scientist to be elevated to the House of Lords. Absolute temperatures are stated in units of kelvin in Lord Kelvin's honour. While the existence of a coldest possible temperature, absolute zero, was known before his work, Kelvin determined its correct value as approximately −273.15 degrees Celsius or −459.67 degrees Fah ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Presidents Of The Royal Society
The president of the Royal Society (PRS), also known as the Royal Society of London, is the elected Head of the Royal Society who presides over meetings of the society's council. After an informal meeting (a lecture) by Christopher Wren at Gresham College, the Royal Society was officially founded on 28 November 1660 when a group of academics decided to found "a College for the Promoting of Mathematical Experimental Learning". King Charles II granted the society a Royal Charter on 15 July 1662, formally establishing it as the "Royal Society of London." The Royal Charter nominated William Brouncker, 2nd Viscount Brouncker, William Brouncker as president and stipulated that future presidents should be elected by the Council and Fellows of the Society at anniversary meetings each year on St. Andrew's Day (30 November). The details of the presidency were described by the second Royal Charter in 1663, which did not set any limit on how long a president could serve. There were considera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Edward Ayrton
William Edward Ayrton, FRS (14 September 18478 November 1908) was an English physicist and electrical engineer. Life Early life and education Ayrton was born in London, the son of Edward Nugent Ayrton, a barrister, and educated at University College School and University College, London. He later studied under Lord Kelvin at Glasgow. India (1868–1872) In 1868, Ayrton went to Bengal in the service of the Indian Government Telegraph department, where he invented a method of detecting faults in lines, which was of great benefit in the maintenance of the overland communications network.Returning to England, Ayrton married Matilda Chaplin. Japan (1873–1879) In 1873, Ayrton accepted an invitation from the Japanese government as Chair of Natural Philosophy and Telegraphy at the new Imperial College of Engineering, Tokyo. He advised the college's architect on the design of the laboratory and demonstration rooms, and is credited with introducing the electric arc light to Ja ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelvin–Helmholtz Instability
The Kelvin–Helmholtz instability (after Lord Kelvin and Hermann von Helmholtz) is a fluid instability that occurs when there is shear velocity, velocity shear in a single continuum mechanics, continuous fluid or a velocity difference across the interface between two fluids. Kelvin-Helmholtz instabilities are visible in the atmospheres of planets and moons, such as in List of cloud types, cloud formations on Earth or the Great Red Spot#Great Red Spot, Red Spot on Jupiter, and the Stellar atmosphere, atmospheres of the Sun and other stars. Theory overview and mathematical concepts Fluid dynamics predicts the onset of instability and transition to turbulent flow within fluids of different density, densities moving at different speeds. If surface tension is ignored, two fluids in parallel motion with different velocities and densities yield an interface that is unstable to short-wavelength perturbations for all speeds. However, surface tension is able to stabilize the short w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelvin Wave
A Kelvin wave is a wave in the ocean, a large lake or the atmosphere that balances the Earth's Coriolis force against a topographic boundary such as a coastline, or a waveguide such as the equator. A feature of a Kelvin wave is that it is non-dispersive, i.e., the phase speed of the wave crests is equal to the group speed of the wave energy for all frequencies. This means that it retains its shape as it moves in the alongshore direction over time. A Kelvin wave (fluid dynamics) is also a long scale perturbation mode of a vortex in superfluid dynamics; in terms of the meteorological or oceanographical derivation, one may assume that the meridional velocity component vanishes (i.e. there is no flow in the north–south direction, thus making the momentum and continuity equations much simpler). This wave is named after the discoverer, Lord Kelvin (1879). Coastal Kelvin wave In a stratified ocean of mean depth ''H'', whose height is perturbed by some amount ''η'' (a functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelvin Water Dropper
The Kelvin water dropper, invented by Scottish scientist William Thomson, 1st Baron Kelvin, William Thomson (Lord Kelvin) in 1867, is a type of electrostatic generator. Kelvin referred to the device as his water-dropping condenser. The apparatus is variously called the Kelvin hydroelectric generator, the Kelvin electrostatic generator, or Lord Kelvin's thunderstorm. The device uses falling water to generate voltage differences by electrostatic induction occurring between interconnected, oppositely Electric charge, charged systems. This eventually leads to an electric arc discharging in the form of a spark. It is used in physics education to demonstrate the principles of electrostatics. Description A typical setup is shown in Fig. 1. A reservoir of water or other conducting liquid (top, grey) is connected to two hoses that release two falling streams of drops, which land in two buckets or containers (bottom, blue and red). Each stream passes (without touching) through a metal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelvin Material
The kelvin (symbol: K) is the base unit for temperature in the International System of Units (SI). The Kelvin scale is an absolute temperature scale that starts at the lowest possible temperature (absolute zero), taken to be 0 K. By definition, the Celsius scale (symbol °C) and the Kelvin scale have the exact same magnitude; that is, a rise of 1 K is equal to a rise of 1 °C and vice versa, and any temperature in degrees Celsius can be converted to kelvin by adding 273.15. The 19th century British scientist Lord Kelvin first developed and proposed the scale. It was often called the "absolute Celsius" scale in the early 20th century. The kelvin was formally added to the International System of Units in 1954, defining 273.16 K to be the triple point of water. The Celsius, Fahrenheit, and Rankine scales were redefined in terms of the Kelvin scale using this definition. The 2019 revision of the SI now defines the kelvin in terms of energy by setting the Bolt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mirror Galvanometer
A mirror galvanometer is an ammeter that indicates it has sensed an electric Current (electricity), current by deflecting a light beam with a mirror. The beam of light projected on a scale acts as a long massless pointer. In 1826, Johann Christian Poggendorff developed the mirror galvanometer for detecting electric currents. The apparatus is also known as a ''spot galvanometer'' after the spot of light produced in some models. Mirror galvanometers were used extensively in scientific instruments before reliable, stable electronic amplifiers were available. The most common uses were as recording equipment for seismometers and submarine communications cable, submarine cables used for telegraphy. In modern times, the term ''mirror galvanometer'' is also used for devices that move laser beams by rotating a mirror through a galvanometer set-up, often with a Servomechanism, servo-like control loop. The name is often abbreviated as ''galvo''. Kelvin's galvanometer The mirror gal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinematic Coupling
Kinematic coupling describes fixtures designed to exactly constrain the part in question, providing precision and certainty of location. A canonical example of a kinematic coupling consists of three radial v-grooves in one part that mate with three hemispheres in another part. Each hemisphere has two contact points for a total of six contact points, enough to constrain all six of the part's degrees of freedom. An alternative design consists of three hemispheres on one part that fit respectively into a tetrahedral dent, a v-groove, and a flat. Background Kinematic couplings arose from the need of precision coupling between structural interfaces that were meant to be routinely taken apart and put back together. Kelvin Coupling The Kelvin coupling is named after William Thompson (Lord Kelvin) who published the design in 1868–71. It consists of three spherical surfaces that rest respectively on a concave tetrahedron, a V-groove pointing towards the tetrahedron and a flat plat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rayleigh's Equation (fluid Dynamics)
In fluid dynamics, Rayleigh's equation or Rayleigh stability equation is a linear theory, linear ordinary differential equation to study the hydrodynamic stability of a parallel, incompressible flow, incompressible and viscosity, inviscid shear flow#In fluid mechanics, shear flow. The equation is: :(U-c) (\varphi'' - k^2 \varphi) - U'' \varphi=0, with U(z) the flow velocity of the steady flow, steady base flow whose stability is to be studied and z is the cross-stream direction (i.e. perpendicular to the flow direction). Further \varphi(z) is the complex valued amplitude of the infinitesimal streamfunction perturbations applied to the base flow, k is the wavenumber of the perturbations and c is the phase speed with which the perturbations propagate in the flow direction. The prime denotes differentiation (mathematics), differentiation with respect to z. Background The equation is named after Lord Rayleigh, who introduced it in 1880. The Orr–Sommerfeld equation – introduced la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binnacle
A binnacle () is a waist-high case or stand on the deck of a ship, generally mounted in front of the helmsman, in which navigational instruments are placed for easy and quick reference as well as to protect the delicate instruments. Its traditional purpose was to hold the ship's magnetic compass, mounted in gimbals to keep it level while the ship pitched and rolled. A binnacle may be subdivided into sections and its contents typically include one or more compasses and an oil lamp or other light source. Other devices such as a sand timer for estimating speed may have been stored in the binnacle as well. Binnacle can also refer to the cluster of instruments and switches mounted in a circular casing on or near the steering column of a car. Etymology Before 18th century ''bittacle'', through French ''bitacle'', from Latin ''habitaculum'', "little dwelling". History The construction of many early (mid-18th century) binnacles used iron nails, which were later discovered to c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ampere Balance
The ampere balance (also current balance or Kelvin balance) is an electromechanical apparatus used for the precise measurement of the SI unit of electric current, the ampere. It was invented by William Thomson, 1st Baron Kelvin. 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. The main weakness of the ampere balance is that the calculation of the current involves the dimensions of the coils. So the accuracy of the current measurement is limited by the accuracy with which the coils can be measured, and their mechanical rigidity. A more complicated version of an ampere balance, that removes this source of inaccuracy by a calibration step, is the Kibble balance, invented by Bryan Kibble ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermoelectric Effect
The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, heat is transferred from one side to the other, creating a temperature difference. This effect can be used to generate electricity, measure temperature or change the temperature of objects. Because the direction of heating and cooling is affected by the applied voltage, thermoelectric devices can be used as temperature controllers. The term "thermoelectric effect" encompasses three separately identified effects: the Seebeck effect (temperature differences cause electromotive forces), the Peltier effect (thermocouples create temperature differences), and the Thomson effect (the Seebeck coefficient varies with temperature). The Seebeck and Peltier effects are different manifestations of the same physical proces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
