List of publications in physics - A Dynamical Theory of the Electromagnetic Field. James Clerk Maxwell Maxwell, James Clerk, "A Dynamical Theory of the Electromagnetic Field". 1865. Description: "A Dynamical Theory of the Electromagnetic Field" was the third of James Clerk Maxwell's papers concerned with electromagnetism. The concept of displacement current was introduced, so that it became possible to derive equations of electromagnetic wave. It was the first paper in which Maxwell's equations appear ...

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List of publications in physics, List of publications in physics - Classical mechanics, List of publications in physics - Philosophiae Naturalis Principia Mathematica, List of publications in physics - Special theory of relativity, List of publications in physics - On the Electrodynamics of Moving Bodies, List of publications in physics - General theory of relativity, List of publications in physics - The Foundation of the General Theory of Relativity, List of publications in physics - Quantum theory, List of publications in physics - On the Law of Distribution of Energy in the Normal Spectrum, List of publications in physics - Thermodynamics, List of publications in physics - An Experimental Enquiry Concerning the Source of the Heat which is Excited by Friction, List of publications in physics - On the Equilibrium of Heterogeneous Substances, List of publications in physics - Statistical mechanics, List of publications in physics - On the Motion—Required by the Molecular Kinetic Theory of Heat—of Small Particles Suspended in a Stationary Liquid, List of publications in physics - Scaling laws for Ising models near Tc, List of publications in physics - The renormalization group: critical phenomena and the Kondo problem, List of publications in physics - Electromagnetism, List of publications in physics - A Dynamical Theory of the Electromagnetic Field, List of publications in physics - Fluid dynamics, List of publications in physics - An experimental investigation of the circumstances which determine whether the motion of water shall be direct or sinuous and of the law of resistance in parallel channels, List of publications in physics - The local structure of turbulence in incompressible viscous fluid for very large Reynolds numbers, List of publications in physics - Statistical fluid mechanics, List of publications in physics - Nonlinear dynamics and chaos, List of publications in physics - Deterministic nonperiodic flow, List of publications in physics - Quantum field theory, List of publications in physics - Space-Time approach to Quantum Electrodynamics, List of publications in physics - Cosmology, List of publications in physics - The Early Universe, List of publications in physics - Condensed matter physics, List of publications in physics - Theory of superconductivity, List of publications in physics - Standard Model, List of publications in physics - Computational physics, List of publications in physics - Accelerator physics, List of publications in physics - Acoustics, List of publications in physics - Astrophysics, List of publications in physics - Cryogenics, List of publications in physics - Polymer physics, List of publications in physics - Optics, List of publications in physics - Materials physics, List of publications in physics - Nuclear physics, List of publications in physics - Plasma physics, List of publications in physics - The Collected Works of Irving Langmuir 1961, List of publications in physics - Cosmical Electrodynamics 2nd ed. 1963, List of publications in physics - Particle physics, List of publications in physics - Vehicle dynamics, List of publications in physics - Astronomy, List of publications in physics - Biophysics, List of publications in physics - Cycles, List of publications in physics - Geophysics, List of publications in physics - Mathematical physics, List of publications in physics - Medical physics, List of publications in physics - Physical chemistry, List of publications in physics - Physics of computation

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Field theory usually refers to a construction of the dynamics of a field, i.e. a specification of how a field changes with time or with respect to other components of the field. Usually this is done by writing a Lagrangian or a Hamiltonian of the field, and treating it as the classical mechanics (or quantum mechanics) of a system with an infinite number of degrees of freedom. The resulting field theories are referred to as classical or quantum field theories. In modern physics, the most often studied fields are those that model the four fundamental forces. See also:

Field physics, Field physics - Field theory, Field physics - Classical fields, Field physics - Quantum fields, Field physics - Symmetries of fields, Field physics - Spacetime symmetries, Field physics - Internal symmetries

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A convenient way of classifying fields (classical or quantum) is by the symmetries it possesses. Physical symmetries are usually of two types: Field physics - Spacetime symmetries. Main articles: Spacetime symmetries, and [[{{{2}}}]], and [[{{{3}}}]] ...

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Field physics, Field physics - Field theory, Field physics - Classical fields, Field physics - Quantum fields, Field physics - Symmetries of fields, Field physics - Spacetime symmetries, Field physics - Internal symmetries

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The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be rapidly manipulated over a wide range by controlling the electric current. A disadvantage is that if an electromagnet with a ferromagnetic core is turned on and off again, the core retains some residual magnetization due to hysteresis. This magnetic field can persist indefinitely. As more electricity is passed through the electromagnet ...

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Electromagnet, Electromagnet - Introduction, Electromagnet - Electromagnets and permanent magnets, Electromagnet - Devices that use electromagnets, Electromagnet - Force on ferromagnetic materials

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Electromagnetic radiation - Theory. Electromagnetic waves of much lower frequency than visible light were predicted by Maxwell's equations and subsequently discovered by Heinrich Hertz. Maxwell derived a wave form of the electric and magnetic equations which made explicit the wave nature of the electric and magnetic fields. These equations displayed the symmetry of the fields. According to the theory, a time-varying electric field generates a magnetic field and vice versa. Thus, an oscillating elect ...

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Electromagnetic radiation, Electromagnetic radiation - Physics, Electromagnetic radiation - Theory, Electromagnetic radiation - Properties, Electromagnetic radiation - Wave model, Electromagnetic radiation - Particle model, Electromagnetic radiation - Speed of propagation, Electromagnetic radiation - Electromagnetic spectrum, Electromagnetic radiation - Light, Electromagnetic radiation - Radio waves, Electromagnetic radiation - Derivation

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The gravitational attraction between protons is approximately a factor of 1036 weaker than the electromagnetic repulsion. This factor is independent of distance, because both interactions are inversely proportional to the square of the distance. Therefore on an atomic scale mutual gravity is negligible. Even so, the main interaction between everyday objects and the Earth and between celestial bodies is gravity, because at this scale matter is electrically neutral. This means that there is an equal number of positively charged part ...

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Gravity, Gravity - Overview of the history of gravitational theory, Gravity - Newton's law of universal gravitation, Gravity - Acceleration due to gravity, Gravity - Bodies with spatial extent, Gravity - Vector form, Gravity - Gravitational field, Gravity - The Earth's gravity, Gravity - Comparative gravities of the Earth Sun Moon and planets, Gravity - Mathematical equations for a falling body, Gravity - Gravitational potential, Gravity - Acceleration relative to the rotating Earth, Gravity - Gravity and astronomy, Gravity - Self-gravitating system, Gravity - Practical uses of gravity, Gravity - Problems with Newton's theory, Gravity - Theoretical concerns, Gravity - Disagreement with observation, Gravity - Newton's reservations, Gravity - Einstein's theory of gravitation, Gravity - Experimental tests, Gravity - Comparison with electromagnetic force, Gravity - Gravity and quantum mechanics, Gravity - Alternative theories, Gravity - Recent alternative theories, Gravity - Historical alternative theories, Gravity - Notes

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The gravitational attraction between protons is approximately a factor of 1036 weaker than the electromagnetic repulsion. This factor is independent of distance, because both interactions are inversely proportional to the square of the distance. Therefore on an atomic scale mutual gravity is negligible. Even so, the main interaction between everyday objects and the Earth and between celestial bodies is gravity, because at this scale matter is electrically neutral. This means that there is an equal number of positively charged part ...

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Gravity, Gravity - Overview of the history of gravitational theory, Gravity - The Earth's gravity, Gravity - Comparative gravities of the Earth Sun Moon and planets, Gravity - Mathematical equations for a falling body, Gravity - Gravitational potential, Gravity - Acceleration relative to the rotating Earth, Gravity - Gravity and astronomy, Gravity - Self-gravitating system, Gravity - Practical uses of gravity, Gravity - Newton's law of universal gravitation, Gravity - Acceleration due to gravity, Gravity - Bodies with spatial extent, Gravity - Vector form, Gravity - Gravitational field, Gravity - Problems with Newton's theory, Gravity - Theoretical concerns, Gravity - Disagreement with observation, Gravity - Newton's reservations, Gravity - Einstein's theory of gravitation, Gravity - Experimental tests, Gravity - Comparison with electromagnetic force, Gravity - Gravity and quantum mechanics, Gravity - Alternative theories, Gravity - Recent alternative theories, Gravity - Historical alternative theories, Gravity - Notes

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The simplest type of electromagnet is a coiled piece of wire. A coil forming the shape of a straight tube (similar to a corkscrew) is called a solenoid; a solenoid that is bent so that the ends meet is a toroid. Much stronger magnetic fields can be produced if a "core" of paramagnetic or ferromagnetic material (commonly iron) is placed inside the coil. The field produced by the coil causes the iron to magnetize and generate a field of its own. This field can be hundreds or thousands o ...

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Electromagnet, Electromagnet - Introduction, Electromagnet - Electromagnets and permanent magnets, Electromagnet - Devices that use electromagnets, Electromagnet - Force on ferromagnetic materials

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Main article: Maxwell's equations The electromagnetic force is best described by Maxwell's theory of electromagnetism. The field equations of classical electromagnetism are Maxwell's equations which describe how electromagnetic fields are produced from charged particles and are written in the framework of special relativity (which was devised to consistently describe ...

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Field equation, Field equation - Newton's theory of universal gravitation, Field equation - Laplace's equation, Field equation - Poisson's equation, Field equation - Einstein's field equation, Field equation - Maxwell's equations, Field equation - Kaluza-Klein field equations

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The general relation for nonlinear materials, the differential energy is: Where V is the volume and dV is the differential volume. For linear materials, H is proportional to B, so the above equation can be simplified: For linear materials and a constant volume: Energy can produce a force, so Where dl is differential distance and A is the surface area. Force per unit area (pressure) is In the case of free space (air), : at BSee also:

Magnetic field, Magnetic field - Symbols and terminology, Magnetic field - Definition, Magnetic field - Current loop, Magnetic field - Point charge generating magnetic field, Magnetic field - Vector calculus, Magnetic field - Energy in the magnetic field, Magnetic field - Properties, Magnetic field - Magnetic field lines, Magnetic field - Pole labeling confusions, Magnetic field - Rotating magnetic fields, Magnetic field - External articles

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Electromagnetic waves as a general phenomenon were predicted by the classical laws of electricity and magnetism, known as Maxwell's equations. If you inspect Maxwell's equations without sources (charges or currents) then you will find that, along with the possibility of nothing happening, the theory will also admit nontrivial solutions of changing electric and magnetic fields. (For symbol definitions see magnetic field.) is a solution, but there might be other solutions as well. Let us employ a us ...

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Electromagnetic radiation, Electromagnetic radiation - Physics, Electromagnetic radiation - Theory, Electromagnetic radiation - Properties, Electromagnetic radiation - Wave model, Electromagnetic radiation - Particle model, Electromagnetic radiation - Speed of propagation, Electromagnetic radiation - Electromagnetic spectrum, Electromagnetic radiation - Light, Electromagnetic radiation - Radio waves, Electromagnetic radiation - Derivation

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Magnetic field is usually denoted by the symbol . Historically, was called the magnetic flux density, magnetic induction, or magnetic field strength. was called the magnetic field (or magnetic field intensity), and this terminology is still often used to distinguish the two in the context of magnetic materials (non-trivial permeability μ). Otherwise, however, this distinction is often ignored, and both symbols are frequently referred to as the magnetic field. (Some authors call H the auxiliary field, instead.) In linear materials, such as air or free space, the ...

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Magnetic field, Magnetic field - Symbols and terminology, Magnetic field - Definition, Magnetic field - Current loop, Magnetic field - Point charge generating magnetic field, Magnetic field - Vector calculus, Magnetic field - Energy in the magnetic field, Magnetic field - Properties, Magnetic field - Magnetic field lines, Magnetic field - Pole labeling confusions, Magnetic field - Rotating magnetic fields, Magnetic field - External articles

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It is widely believed that three of the four fundamental forces (the strong nuclear force, the weak nuclear force, and the electromagnetic force) are manifestations of a single, more fundamental force. Combining gravity with these forces of quantum mechanics to create a theory of quantum gravity is currently an important topic of research amongst physicists. General relativity is an essentially geometric theory that requires no exchange of particles in its explanation of gravity, whereas quantum mechanics relies on interactions betwee ...

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Gravity, Gravity - Overview of the history of gravitational theory, Gravity - Newton's law of universal gravitation, Gravity - Acceleration due to gravity, Gravity - Bodies with spatial extent, Gravity - Vector form, Gravity - Gravitational field, Gravity - The Earth's gravity, Gravity - Comparative gravities of the Earth Sun Moon and planets, Gravity - Mathematical equations for a falling body, Gravity - Gravitational potential, Gravity - Acceleration relative to the rotating Earth, Gravity - Gravity and astronomy, Gravity - Self-gravitating system, Gravity - Practical uses of gravity, Gravity - Problems with Newton's theory, Gravity - Theoretical concerns, Gravity - Disagreement with observation, Gravity - Newton's reservations, Gravity - Einstein's theory of gravitation, Gravity - Experimental tests, Gravity - Comparison with electromagnetic force, Gravity - Gravity and quantum mechanics, Gravity - Alternative theories, Gravity - Recent alternative theories, Gravity - Historical alternative theories, Gravity - Notes

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It is widely believed that three of the four fundamental forces (the strong nuclear force, the weak nuclear force, and the electromagnetic force) are manifestations of a single, more fundamental force. Combining gravity with these forces of quantum mechanics to create a theory of quantum gravity is currently an important topic of research amongst physicists. General relativity is an essentially geometric theory that requires no exchange of particles in its explanation of gravity, whereas quantum mechanics relies on interactions betwee ...

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Gravity, Gravity - Overview of the history of gravitational theory, Gravity - The Earth's gravity, Gravity - Comparative gravities of the Earth Sun Moon and planets, Gravity - Mathematical equations for a falling body, Gravity - Gravitational potential, Gravity - Acceleration relative to the rotating Earth, Gravity - Gravity and astronomy, Gravity - Self-gravitating system, Gravity - Practical uses of gravity, Gravity - Newton's law of universal gravitation, Gravity - Acceleration due to gravity, Gravity - Bodies with spatial extent, Gravity - Vector form, Gravity - Gravitational field, Gravity - Problems with Newton's theory, Gravity - Theoretical concerns, Gravity - Disagreement with observation, Gravity - Newton's reservations, Gravity - Einstein's theory of gravitation, Gravity - Experimental tests, Gravity - Comparison with electromagnetic force, Gravity - Gravity and quantum mechanics, Gravity - Alternative theories, Gravity - Recent alternative theories, Gravity - Historical alternative theories, Gravity - Notes

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Like the electric field, the magnetic field can be defined by the force it produces. In SI units, this is: where F is the force produced, measured in newtons indicates a vector cross product is electric charge that the magnetic field is acting on, measured in coulombs is velocity of the electric charge , measured in metres per second B is mag ...

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Magnetic field, Magnetic field - Symbols and terminology, Magnetic field - Definition, Magnetic field - Current loop, Magnetic field - Point charge generating magnetic field, Magnetic field - Vector calculus, Magnetic field - Energy in the magnetic field, Magnetic field - Properties, Magnetic field - Magnetic field lines, Magnetic field - Pole labeling confusions, Magnetic field - Rotating magnetic fields, Magnetic field - External articles

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Maxwell did much to unify static electricity and magnetism, producing a set of four equations relating the two fields. However, under Maxwell's formulation, there were still two distinct fields describing different phenomena. It was Albert Einstein who showed, using special relativity, that electric and magnetic fields are two aspects of the same thing (a rank-2 tensor), and that one observer may perceive a magnetic force where a moving observer perceives only an electrostatic force. Thus, using special relativity, magnetic forces are a mani ...

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Magnetic field, Magnetic field - Symbols and terminology, Magnetic field - Definition, Magnetic field - Current loop, Magnetic field - Point charge generating magnetic field, Magnetic field - Vector calculus, Magnetic field - Energy in the magnetic field, Magnetic field - Properties, Magnetic field - Magnetic field lines, Magnetic field - Pole labeling confusions, Magnetic field - Rotating magnetic fields, Magnetic field - External articles

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Electromagnets are used in many situations where a rapidly or easily variable magnetic field is desired. Many of these applications involve deflection of charged particle beams; the cathode ray tube and mass spectrometer fall into this category. Other devices cause electromagnetic fields to interact with fields from permanent magnets and produce forces. Electromagnetic actuators take advantage of the fact that, if the core of a solenoid is displaced toward one end of the coil, a force will occur tending to push the core farther in tha ...

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Electromagnet, Electromagnet - Introduction, Electromagnet - Electromagnets and permanent magnets, Electromagnet - Devices that use electromagnets, Electromagnet - Force on ferromagnetic materials

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This can be in any range of wavelengths: Radio waves Microwaves Infrared light (see infrared spectroscopy) Visible light (see UV/visible spectroscopy) Ultraviolet light (see UV/visible spectroscopy) X-rays Electromagnetic spectroscopy can be classified into narrower fields as discussed below, though in some spectroscopic techniques, several processes may be happening at the same time. ...

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Electromagnetic spectroscopy, Electromagnetic spectroscopy - Types of electromagnetic radiation measured, Electromagnetic spectroscopy - Types of electromagnetic spectroscopy, Electromagnetic spectroscopy - Emission spectroscopy, Electromagnetic spectroscopy - Absorption spectroscopy, Electromagnetic spectroscopy - Other techniques, Electromagnetic spectroscopy - Examples, Electromagnetic spectroscopy - The spectrum of sunlight, Electromagnetic spectroscopy - Absorption in the atmosphere

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Gravity - Recent alternative theories. Brans-Dicke theory of gravity Rosen bi-metric theory of gravity In the modified Newtonian dynamics (MOND), Mordehai Milgrom proposes a modification of Newton's Second Law of motion for small accelerations. Gravity - Historical alternative theories. Nikola Tesla challenged Albert Einstein's theory of relativity, announcing he was working on a Dynamic theory of gravity (which began between 1892 and ...

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Gravity, Gravity - Overview of the history of gravitational theory, Gravity - Newton's law of universal gravitation, Gravity - Acceleration due to gravity, Gravity - Bodies with spatial extent, Gravity - Vector form, Gravity - Gravitational field, Gravity - The Earth's gravity, Gravity - Comparative gravities of the Earth Sun Moon and planets, Gravity - Mathematical equations for a falling body, Gravity - Gravitational potential, Gravity - Acceleration relative to the rotating Earth, Gravity - Gravity and astronomy, Gravity - Self-gravitating system, Gravity - Practical uses of gravity, Gravity - Problems with Newton's theory, Gravity - Theoretical concerns, Gravity - Disagreement with observation, Gravity - Newton's reservations, Gravity - Einstein's theory of gravitation, Gravity - Experimental tests, Gravity - Comparison with electromagnetic force, Gravity - Gravity and quantum mechanics, Gravity - Alternative theories, Gravity - Recent alternative theories, Gravity - Historical alternative theories, Gravity - Notes

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According to Equation (1) above, electric field is dependent on position. The electric field due to any single charge falls off as the square of the distance from that charge. Electric fields follow the superposition principle. If more than one charge is present, the total electric field at any point is equal to the vector sum of the respective electric fields that each object would create in the absence of the others. If this principle is extended to an infinite number of infinitesimally small elements ...

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Electric field, Electric field - Definition and derivation for electrostatics, Electric field - Properties in electrostatics, Electric field - Parallels between electrostatics and gravity, Electric field - Time-varying fields

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Computing the force on ferromagnetic materials is, in general, quite complex. This is due to fringing field lines and complex geometries. It can be simulated using finite element analysis. However, it is possible to estimate the maximum force under specific conditions. If the magnetic field is confined within a high permeability material, such as certain steel alloys, the maximum force is given by: Where: F is the force in newtons B is the magnetic field in teslas A is the area of the pole faces in square ...

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Electromagnet, Electromagnet - Introduction, Electromagnet - Electromagnets and permanent magnets, Electromagnet - Devices that use electromagnets, Electromagnet - Force on ferromagnetic materials

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The mathematical definition of the electric field is developed as follows. Coulomb's law gives the force between two point charges (infinitesimally small charged objects) as where ε0 (pronounced epsilon-nought) is a physical constant, the permittivity of free space; q1 and q2 are the electric charges of the objects; rSee also:

Electric field, Electric field - Definition and derivation for electrostatics, Electric field - Properties in electrostatics, Electric field - Parallels between electrostatics and gravity, Electric field - Time-varying fields

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