A machine is any device that uses energy to perform some activity. In common usage, the meaning is that of a device having parts that perform or assist in performing any type of work. A simple machine is a device that transforms the direction or magnitude of a force without consuming any energy. The word "machine" is derived from the Latin machina.
Magnetic circuit
The concept of a 'magnetic circuit' exploits a one to one correspondence between the equations of the magnetic field in a non-hysteretic material to that of an electrical circuit. Using this concept the magnetic fields of complex devices such as transformers can be quickly solved using the methods and techniques developed for electrical circuits.
A magnetic circuit is made up of one or more closed paths containing a magnetic flux. It generally contains magnetic elements such as permanent magnets, ferromagnetic materials, and electromagnets, but may also contain air gaps and other materials.
Some examples of magnetic circuits are:
horseshoe magnet with iron keeper (low-reluctance circuit)
horseshoe magnet with no keeper (high-reluctance circuit)
electric motor (variable-reluctance circuit)
Magnetic flux
Magnetic flux, represented by the Greek letter F (phi), is a measure of quantity of magnetism, taking into account the strength and the extent of a magnetic field. The SI unit of magnetic flux is the weber (in derived units: volt-seconds), and the unit of magnetic field is the weber per square meter, or tesla.
Magnetic moment
The magnetic moment of a system is a measurement of the magnetic strength and direction used in physics, astronomy, chemistry, and electrical engineering. More technically, the term magnetic moment of a system (such as a loop of electric current, a bar magnet, an electron, a molecule, or a planet) usually refers to its magnetic dipole moment, and quantifies the contribution of the system's internal magnetism to the external dipolar magnetic field produced by the system (that is, the component of the external magnetic field that drops off with distance as the inverse cube). Any dipolar magnetic field pattern is symmetric with respect to rotations around a particular axis, therefore it is customary to describe the magnetic dipole moment that creates such a field as a vector with a direction along that axis. For quadrupolar, octupolar, and higher-order multipole magnetic moments, see Multipole expansion.
Magnetostatics
Magnetostatics is the study of static magnetic fields. In electrostatics, the charges are stationary, whereas here, the currents are stationary or dc(direct current). As it turns out magnetostatics is a good approximation even when the currents are not static as long as the currents do not alternate rapidly.
Mass transfer
Mass transfer is the transfer of mass from high concentration to low concentration. The phrase is commonly used in engineering for physical processes that involve molecular and convective transport of atoms and molecules within physical systems. Mass transfer includes both fluid flow and separation unit operations.
Material
Material is synonymous with Substance, and is anything made of matter - hydrogen, air and water are all examples of materials. Sometimes the term Material is used more narrowly to refer to substances or components with certain physical properties which are used as inputs to production or manufacturing. In this sense, materials are the pieces required to make something else, from buildings and art to stars and computers.
A material can be anything: a finished product in its own right or an unprocessed raw material. Raw materials are first extracted or harvested from the earth and divided into a form that can be easily transported and stored, then processed to produce semi-finished materials. These can be input into a new cycle of production and finishing processes to create finished materials, ready for distribution, construction, and consumption.
An example of a raw material is cotton, which is harvested from plants, and can then be processed into thread (also considered a raw material), which can then be woven into cloth, a semi-finished material. Cutting and sewing the fabric turns it into a garment, which is a finished material. Steelmaking is another example—raw materials in the form of ore are mined, refined and processed into steel, a semi-finished material. Steel is then used as an input in many other industries to make finished products.
Maxwell's equations
In electromagnetism, Maxwell's equations are a set of four partial differential equations that describe the properties of the electric and magnetic fields and relate them to their sources, charge density and current density. These equations are used to show that light is an electromagnetic wave. Individually, the equations are known as Gauss's law, Gauss's law for magnetism, Faraday's law of induction, and Ampère's law with Maxwell's correction.
These four equations, together with the Lorentz force law are the complete set of laws of classical electromagnetism. The Lorentz force law itself was actually derived by Maxwell under the name of "Equation for Electromotive Force" and was one of an earlier set of eight Maxwell's equations.
Measurement
Measurement is the process of assigning a number to an attribute (or phenomenon) according to a rule or set of rules. The term can also be used to refer to the result obtained after performing the process.
Mechanics
Mechanics (Greek ???a????) is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment. The discipline has its roots in several ancient civilizations (see History of classical mechanics and Timeline of classical mechanics). During the early modern period, scientists such as Galileo, Kepler, and especially Newton, laid the foundation for what is now known as classical mechanics.
Mechatronics
Mechatronics (or Mechanical and Electronics Engineering) is the synergistic combination of mechanical engineering, electronic engineering, control engineering, systems design engineering, and computer engineering to create useful products. The purpose of this interdisciplinary engineering field is the study of automata from an engineering perspective and serves the purposes of controlling advanced hybrid systems. The word itself is a combination of 'Mechanics' and 'Electronics'.
Melting
Melting (sometimes called fusion) is a physical process that results in the phase change of a substance from a solid to a liquid. The internal energy of a solid substance is increased, typically by the application of heat or pressure, resulting in a rise of its temperature to the melting point, at which the rigid ordering of molecular entities in the solid breaks down to a less-ordered state and the solid liquefies. An object that has melted completely is molten.
Metallography
Metallography is the study of the physical structure and components of metals, typically using microscopy.
Ceramic and polymeric materials may also be prepared using metallographic techniques, hence the terms ceramography, plastography and, collectively, materialography.
Microcontroller
A microcontroller (also microcontroller unit, MCU or µC) is a small computer on a single integrated circuit consisting of a relatively simple CPU combined with support functions such as a crystal oscillator, timers, watchdog, serial and analog I/O etc. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a, typically small, read/write memory.
Microprocessor
A microprocessor incorporates most or all of the functions of a central processing unit (CPU) on a single integrated circuit (IC). The first microprocessors emerged in the early 1970s and were used for electronic calculators, using binary-coded decimal (BCD) arithmetic on 4-bit words. Other embedded uses of 4- and 8-bit microprocessors, such as terminals, printers, various kinds of automation etc, followed rather quickly. Affordable 8-bit microprocessors with 16-bit addressing also led to the first general purpose microcomputers in the mid-1970s. The recent development of fast microprocessors is also linked to the growing popularity of fourth generation programming languages.
Elastic modulus
An elastic modulus, or modulus of elasticity, is the mathematical description of an object or substance's tendency to be deformed elastically (i.e., non-permanently) when a force is applied to it. The elastic modulus of an object is defined as the slope of its stress-strain curve in the elastic deformation region:
Moment (physics)
In physics, the term "moment" can refer to many different concepts:
Moment of force (often just moment) is a synonym for torque, an important basic concept in physics, civil engineering, and mechanical engineering. In the context of mechanical engineering, the terms are not necessarily interchangeable, but one or the other may be preferred in a specific context. For example, "torque" is usually used to describe a rotational force of a shaft, for example a turning screw-driver, while "moment" is more often used to describe a bending force on a beam.
Moment arm is a quantity used when calculating torque. See the article torque.
The Principle of moments is a theorem concerning torques. See the article torque.
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