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Kapitza Balance - A magnetic balance designed for the measurement of susceptibilities in large magnetic fields when the force is large and applied only momentarily. It is not suitable for absolute measurements.
Karman Similarity Theory - Of turbulent now
in fluids: states that the local now pattern is statistically similar at or near all points in the fluid, only the time and length scales being different.
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Katathermometer - A form of mercury thermometer for measuring the rate of-cooling of the body, used, for example in mining to estimate the degree of comfort experienced. It is used to find the time taken for the mercury to drop from 38° C to 35° C.
Katharometer - An instrument for determining the composistion of a mixture of known gases by the measurement of thermal conductivity as revealed by the cooling effect of the gas as it flows past a heated wire or thermistor.
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Kelvin - The unit of thermodynamic temperature, formerly called the degree Kelvin. It is 1/273.16 of the thermodynamic temperature of the triple point of water.
Kelvin Theorem - For fluid flow: states that, in a region of now in which the entropy is constant, the circulation around a closed path moving with fluid also remains constant. In other words, vorticity cannot be created or annihilated inside a homentropic region of fluid flow.
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Kenotron - A high-voltage (above 10 k V) thermionic diode rectifier.
Kepler Laws - Three laws which initiated the modern mathematical treatment of planetary motions. They may be stated as follows: (a) Every planet moves in an ellipse of which one focus is the Sun. (b) The radius vector from the Sun to a planet sweeps, out equal areas in equal times. (c) The squares of the periodic times which the various planets take to describe their respective orbits are proportional to the cubes of their respective orbits are proportional to the cubes of their mean distances from the Sun, the mean distance being taken as the length of the semi-major axis.
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Kerr Cell - A fast optical shutter employing the Kerr effect. It consists essentially of a call containing all optically transparent isotropic material (solid or liquid) and a pair of plates for applying a large electric field across it. Between crossed nicol prisms (or crossed polaroids) no light passes through the cell until the field is turned on. Such cells have been employed in television equipment. in the determination of the speed of light and in measuring the decay times of flouresecent phenomena.
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Kerr Effect - (1) Elecro-optical: the occurrence of birefringence in a transparent isotorpic medium when it is placed in an electric field. ,The medium then behaves like a uniaxial crystal with its optic axis lying in the direction of the field. (2) Magneto-optical: the occurrence of elliptical polarization in plane polarized light when it is reflected from the pole of a magnet.
Kilogramme - The unit of mass in the MKS and International (SI) systems. It is the mass of a standard platinum-10% iridium alloy in the form of a cylinder which is kept at the Bureau International des Po ids et Mesures in Sevres.
Kilogramme Force: Kilogramme Weight - The force with which a mass of 1 kg is attracted by the Earth. It is equal at Sevres to 9.80665 N.
Kinematics - The study of the motion of particles and bodies Without reference to the forces associated with that motion. Its three basic paramenters are displacement. rate of change of displacement, and rate of change of velocity (i.e. acceleration).
Kinematic Viscosity - The coefficient of viscosity of a fluid divided by it density. It measures the kinematic effect of the viscosity Typical values at 20° C are: for water 0.01 cm2 s -1 and for glycerine 6.8 cm2 s-1.The CGS unit of kinematic viscosity is the stokes, which is exactly equal to 10-4 m2 s-1 the (unnamed) SI unit being m2s-1.
Kinetic Energy - Energy stored in a system by virtue of the velocities of various moving masses within the system. The kinetic energy of a body of mass m and velocity v is 1/2m2.
Kinetic Head: Velocity Head - For a perfect fluid in study flow: one-half the ratio of the square of the flow velocity to the gravitational acceleration. It is the height of a column of fluid giving a hydrostatic pressure of 1/2qv2 where q is the density and v the flow velocity. Pressure head + Velocity (or Kinetic) head + Elevation head=constant, according to the Bernoulli equation.
Kinetic Momentum - Of a charged particle in an electromagnetic field the vector p- (e/c) A, where A is the field, p the momentum, ethe charge, and e the speed of light.
Kinetic Theory of Gases - The theory which relates the macroscopic properties of a gas to the motion of its individual molecules. It assumes thin heat can be identified with molecular motion, that the molecules can he regarded as elastic sphere, that the interaction of gas molecules with each other and with the walls of the container may be treated according to the laws of classical mechanics, and that the methods of statistical analysis may be used.
Kirchhoff Laws of Electrical Networks - For electrical networks carrying steady currents: state (a) that the sum of all currents flowing towards a node of the network is zero, a node denoting a common junction of several conductors; and (b) that the sum of the voltages encountered in traversing the network along g a closed loop is zero.
Kirchhoff Radiation Law - States that the ratio of the emissive power to the absorptive power for thermal radiation of a given wavelength is the same for all bodies at the same temperature and is equal to the emissive power of a black body at that temperature.
Kirchhoff Vapour. Pressure Formula - For the variation of vapour pressure with temperature: may be stated as In p = A (B/T) -C In T, where p is the vapour pressure, T the temperature, and A, B and C are constants. It is valid only over a limited range of temperature.
Klein-Nishina Formula - An expression for the total or differential cross-section of an unbound electron for the Compton scattering of a photon, according to Dirac' s electron theory.
Klystron - A velocity-modulated elctron beam tube for the generation of very-high-frequency oscillations at high power. It consists of an electron gun, drift tunnel (with usually not less than two reasonant cavities--the buncher and the catcher), and a beam collector:
Knudsen Absolute -Manometer - A vacuum gauge for the absolute measurement of low pressure, involving the measurement of the repulsion exerted between two closely-spaced metal surfaces when a small temperature difference is maintained between them.
Knudsen Flow - The flow of gas through a long tube at pressure such that the mean free path of the gas molecules is such greater than the radius of the tube.
Knudsen Number - A parameter hlL, where λ is the mean free path of the molecules and L is a characteristic length, which is important in the case of fluid flow of low molecular density.
Kopp Law - States that the specific heat of a solid element is the same whether it is free or part of a solid compound. Alternatively: the molar heat of a solid compound is equal to the sum of the atomic heats of its constituents.
Kossel Effect - The production of a series of cones of reflected X-rays when characteristic X-rays are generated within a single crystal (e.g. by an electron or X-ray beam). These cones, recorded on a film, manifest themselves as ellipses, parabolae and hyperbolae, which are known as Kossel lines.
Kundt Tube - For the measurement of the speed of sound in gases: a tube containing a light powder which reveals the positions of the nodes when stationary sound waves of known frequency are set up in the tube, thus giving the wavelength and hence, the speed.
Kurie Plot: Fermi Plot - Of a β-particle spectrum: a graph in which a suitable function of the observed intensity is plotted against the particle energy. the function being chosen so that the graph is a straight line for allowed β-transitions. It is used in determining the character of the β-transition and the maximum energy.
Kymography - A method of recording in a single radiograph the excurisons of a moving organ (such as heart or stomach) in the body.
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