Dipole - Dipole A dipole is a pair of electric charges or magnetic poles of equal magnitude but opposite polarity, separated by some (usually small) distance. Dipoles can be characterized by their dipole moment, a vector quantity with a magnitude equal to the product of the charge or magnetic strength of one of the poles and the distance separating the two poles. The direction of the dipole moment corresponds to the direction from the negative to the positive charge or from the south to the north pole. (Because of the absence of magnetic monopoles, magnetic dipoles are actually created by current loops or by quantum-mechanical spin.) When placed in an electric (E) or magnetic (B) field, equal but opposite forces arise on each side of the dipole creating.
Intermolecular force - decreasing strength, these forces are: Ionic interactions Hydrogen bonds Dipole-dipole interactions London Dispersion Forces Table of contents showTocToggle("show","hide") 1 Ionic Interactions 2 Hydrogen Bonding 3 Dipole-Dipole Interactions 4 London Dispersion Forces Ionic Interactions This is an interactions that occurs between charged species, like charges will have a repulsive force while opposite charges will have an attractive force. Hydrogen Bonding hydrogen bonding can be formed when a hydrogen atom is bound to a highly electronegative atom such as nitrogen, oxygen, or fluorine. The hydrogen atom has a partial positive charge and can interacts with another electronegative atoms found in a different molecule (again N, O, or F). This results in a stabilizing interaction that loosely binds the two molecules together. A common example is water: H20---H-O-H Hydrogen bonds are found throughout nature..
Isotropic antenna - no actual physical isotropic antenna; a close approximation is a stack of two pairs of crossed dipole antennas driven in quadrature. Antenna gains are often specified in dBi, or decibels over isotropic. This is the power in the strongest direction divided by the power that would be transmitted by an isotropic antenna emitting the same total power..
Gauge field theory - not always obvious in the states one sees in nature. Sometimes, especially when temperature decreases, the symmetry gets spontaneously broken. A basic example of broken symmetry that is often given is a solid state magnet. It is composed of many atoms, each of which has a magnetic dipole moment. However, the laws of magnetism are rotationally symmetric, and so at high temperatures, the atoms will be randomly aligned, and the rotational symmetry will be restored. Similarly, you can, under the right conditions, super-cool water to below freezing point. When an ice crystal is dropped into the liquid, the symmetry is broken and it solidifies instantly..
Glossary of antenna terms - beam diameter -- beam divergence -- beam steering -- beamwidth -- biconical antenna -- billboard antenna -- boresight -- Cassegrain antenna -- collinear antenna array -- corner reflector -- counterpoise -- departure angle -- despun antenna -- diplex operation -- dipole antenna -- directional antenna -- direct ray -- effective antenna gain contour (of a steerable satellite beam) -- effective boresight area (of a steerable satellite beam) -- effective height -- effective isotropically radiated power (e.i.r.p.) -- effective monopole radiated power (e.m.r.p.) (in a given direction) -- effective radiated power (e.r.p.) (in a given direction) -- fan-beam antenna -- far-field radiation pattern -- far-field region -- feed -- Fractal antenna -- Fresnel zone -- front-to-back ratio -- ground plane -- helical antenna -- heterodyne repeater -- horn -- hybrid coupler --.
Ferromagnetism - are attracted to them). Some examples of ferromagnetic materials are iron, cobalt, nickel, and gadolinium. Physical origin The property of ferromagnetism is due to the direct influence of two effects from quantum mechanics: spin and the Pauli exclusion principle. The spin of an electron has a magnetic dipole moment and creates a magnetic field. (The classical analogue of quantum-mechanical spin is a spinning ball of charge, but the quantum version has distinct differences, such as the fact that it has discrete up/down states that are not described by a vector.) In many materials (specifically those with a filled electron shell), however, the electrons come in pairs of opposite spin, which cancel one another's dipole moments. Only atoms with unpaired electrons (partially filled shells) can experience a net magnetic moment from spin..
Ferroelectric effect - an electrical phenomenon whereby certain crystals may exhibit a spontaneous dipole moment (which is called ferroelectric by analogy with ferromagnetic - exhibiting a permanent magnetic moment). The effect in the most typical case, barium titanate, is due to a polarization catastrophe, in which the local electric fields due to the polarization itself increase faster than the elastic restoring forcess on the ions in the crystal, thereby leading to an asymmetrical shift in ionic positions and hence to a permanent dipole moment. Ferroelectric crystals often show several Curie points, domain structure hysteresis, much as do ferromagnetic crystals..
Earth's magnetic field - The magnetic field extends several tens of thousands of kilometers into space. The field is approximately a magnetic dipole, with one pole near the geographic north pole and the other near the geographic south pole. An imaginary line joining the magnetic poles would be inclined by approximately 11.3° from the planet's axis of rotation. The field is similar to that of a bar magnet, but this similarity is superficial. The magnetic field of a bar magnet, or any other type of permanent magnet, is created by the coordinated motions of electrons (negatively charged particles) within iron atoms. The Earth's core, however, is hotter than 1043 K, the temperature at which the orientations of electron orbits within iron become randomized. Such randomization tends to cause the substance to lose its magnetic field..
EDM - motion Earthquake disaster mitigation Electric dipole moment Electrical discharge machining Electronic dance music Electronic distance meter Engineering design management Environmental design and management Department of Essential Drugs and Medicines of the World Health Organization.
Effective radiated power - the amount of power that would have to be fed into a standard dipole antenna, to make it as effective as the antenna it is being compared to. It does not account for height, only for antenna gain..
Diode - to conduct "backwards". This effect, called Zener Breakdown, occurs at a precisely defined voltage, allowing the diode to be used as a precision voltage reference. Some devices labelled as high-voltage Zener diodes are actually avalanche diodes (see below). Avalanche diodes: diodes that conduct in the reverse direction when the reverse bias voltage exceeds the breakdown voltage. These are electrically very similar to Zener diodes, and are often mistakenly called Zener diodes, but break down by a different mechanism, the Avalanche Effect. This occurs when the reverse electric field across the p-n junction causes a wave of ionization, reminiscent of an avalanche, leading to a large current. Avalanche diodes are designed to break down at a well-defined reverse voltage without being destroyed. Light emitting diodes (LEDs): as the electrons cross the junction.
T2FD Antenna - Antenna The T2FD (tilted, terminated, folded dipole) is a general-purpose shortwave antenna developed in the late 1940s by the United States Navy. It performs reasonably well (if not with optimal efficiency) over a wide frequency range and without marked dead spots in terms of frequency or direction. While in many ways measurably inferior to antennas specifically designed for given frequency bands, or optimized for directionality, its all-around performance, relatively modest size, low cost, and the fact that it does not require any electronic matching to operate with a standard shortwave transmitter, have made it popular in professional shortwave communications. Since the late 1980s also amateur radio operators and hobby shortwave listeners have become aware of its qualities. A typical T2FD is built as follows, out of wire conductors: Length equal to.
Antenna gain - antenna in a particular direction, compared with the sensitivity of an isotropic antenna in any direction, or a dipole antenna in the equatorial direction. The two measurements are measured in decibels and denoted by dBi and dBd respectively..
Astrochemistry - As such, it represents an overlap of the disciplines of astronomy and chemistry. The most common molecule H2, does not have a dipole moment, so it is not easily detectable. Much easier to detect is the CO molecule. Hundreds of types of molecules have been observed so far, even complex ones as amino acids. There is active ongoing research on the way this molecules form and interact. This can have an impact even in our undestanding of the origin of life on earth. See also: Interstellar cloud Interstellar medium Nebula.
Tevatron - it can increase antiproton energy to 120 GeV and it inject protons or antiprotons into the Tevatron. The antiprotons are created by the Antiproton Source, 120 GeV protons are collided with a nickel target producing a range of particles including antiprotons which can be collected and stored in the accumulator ring. The ring can then pass the antiprotons to the Main Injector. The Tevatron can accelerate the particles from the Main Injector up to 1 TeV (actually 980 GeV), within 320 km/hr of the speed of light. The protons and antiprotons are accelerated in opposite directions, crossing paths in the CDF and D0 (zero) detectors to collide at 1.96 TeV. To hold the particles on track the Tevatron uses superconducting dipole magnets cooled in liquid helium producing 4.2 Tesla..
Bel - the ratio between two measurements of electrical power. It can also be combined with a suffix to create an absolute unit of electrical power. For example, it can be combined with "m" for "milliwatt" to produce the "dBm". 0 dBm is one milliwatt, and 1dBm is one decibel greater than 0 dBm, or about 1.259 mW. Although decibels were originally used for power ratios, they are nowadays commonly used in electronics to describe voltage or current ratios. In a constant resistive load, power is proportional to the square of the voltage or current in the circuit. Therefore, the decibel ratio of two voltages V1 and V2 can be defined as 20 log10(V1/V2), and similarly for current ratios. Thus, for example, a factor of 2.0 in voltage is equivalent to 6.02 dB.
Billboard antenna - In telecommunication, a billboard antenna is an array of parallel dipole antennas with flat reflectors, usually positioned in a line or plane. Note 1: The spacing and dimensions of the dipoles depend on the wavelength. Note 2: The main lobe of a fixed billboard antenna may, within limits, be steered by appropriate phasing of the respective signals to individual elements of the array. Synonym broadside antenna. Source: from Federal Standard 1037C.
Biconical antenna - current) at the vertex. The conductors have a common axis and vertex. The two cones face in opposite directions. Biconical antennas are broadband dipole antennas transcieving signals from 30 MHz to 300 MHz. If one of the cone's angle at the vertex is 180 degrees (or if one of the cones is reduced to a plane), it is called a discone. A simple conical monopole antenna is a wire approximation of the solid biconical antenna and has increased bandwidth (over a simple monopole). A bowtie antenna is simple broadband wire approximation of a biconical antenna (commonly used for UHF transception). See also: Antenna, Radio, Television External Links, references, resources Biconical antenna Biconical Antennas Tim's Discone Antenna UHF Discone Antenna The Discone Antenna Discone Antenna [PDF].
Boiling point - a gas requires an amount of heat called the latent heat of vaporization. As heat is added to a liquid at its boiling point, all of this heat goes toward the phase change from liquid to gas, thus the temperature of the substance remains constant even though heat has been added. The word latent, which comes from Latin and means hidden, is used to describe this "disappearing" heat that is added, but doesn't result in an increase in temperature. Since heat is added with no corresponding change in temperature, the heat capacity of the liquid is essentially infinite at the boiling point. In terms of intermolecular interactions, the boiling point represents the point at which the liquid molecules possess enough heat energy to overcome the various intermolecular attractions binding the molecules.
Carbon monoxide - to reduce suicide by this route, as catalytic converters designed to clean up the exhausts remove all but a trace of CO. During World War II, the Nazis devised a portable gas chamber for their murder of Jews and other minorities: the so-called `gas van', a Diesel engine van, with the CO-laden exhaust piped into the back of the van. A major problem of accidental CO poisoning that still exists is the use of heaters, particularly gas water heaters and gas fires which are improperly vented. There are a number of deaths every year from this cause. Physiological Role Carbon monoxide is produced naturally by the body. The breakdown-product of hemoglobin, heme, is a substrate for the enzyme heme oxygenase which produces CO and biliverdin. The biliverdin can then be reduced.
