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A Helmholtz coil Helmholtz coil schematic drawing. A Helmholtz coil is a device for producing a region of nearly uniform magnetic field, named after the German physicist Hermann von Helmholtz. It consists of two electromagnets on the same axis, carrying an equal electric current in the same direction. Besides creating magnetic fields, Helmholtz ...
The Sommerfeld radiation condition is used to solve uniquely the Helmholtz equation. For example, consider the problem of radiation due to a point source in three dimensions, so the function in the Helmholtz equation is () = (), where is the Dirac delta function. This problem has an infinite number of solutions, for example, any function of the ...
The Helmholtz equation has a variety of applications in physics and other sciences, including the wave equation, the diffusion equation, and the Schrödinger equation for a free particle. In optics, the Helmholtz equation is the wave equation for the electric field. [1] The equation is named after Hermann von Helmholtz, who studied it in 1860. [2]
In migratory soprano pipistrelles (Pipistrellus pygmaeus), experiments using mirrors and Helmholtz coils show that they calibrate the magnetic field using the position of the solar disk at sunset. [71] [72] Red foxes (Vulpes vulpes) may be influenced by the Earth's magnetic field when predating small rodents like mice and voles. They attack ...
Helmholtz coil An arrangement of coils useful for producing a uniform magnetic field within a certain volume. henry The SI unit of inductance. Hertz The SI unit of frequency, equivalent to one cycle per second. heterodyne The process of mixing signals of a number of frequencies to produce new frequencies. heterostructure
A beam of cathode rays in a vacuum tube bent into a circle by a magnetic field generated by a Helmholtz coil.Cathode rays are normally invisible; in this demonstration Teltron tube, enough gas has been left in the tube for the gas atoms to luminesce when struck by the fast-moving electrons.
The original PEMF devices consisted of a Helmholtz coil which generated a magnetic field. The patient's body was placed inside the magnetic field to deliver treatment. Today, the majority of PEMF wellness devices resemble a typical yoga mat in dimensions but are slightly thicker to house several flat spiral coils to produce an even electromagnetic
In 1934, Braunbek developed the Braunbek coil, a modified Helmholtz coil. In 1939, he disproved Earnshaw's theorem by showing that there are magnetic fields in which small diamagnetic bodies can float in a stable position. [2] He pioneered study into the diffraction of waves, particularly at short wavelengths.