A speaker design which generates equal amounts of sound both forward and backward, with the two sounds being out of phase Dipoles are often used as surround speakers See also Bipole
A molecule which has a definite separation between its center of positive charge and center of negative charge Such a molecule is said to be polar A polar species will be more attracted to a charged species than will a non-polar one
A speaker where the sound emanates from the sides of the monitors, which provides the advantage of additional coverage area A Dipole works well for ambience material but not as well for direct source material
A type of antenna with two defined opposing radiating elements, both of the proper length for the frequency of operation, and each forming the counterpoise for the other
a compact source of magnetic force, with two magnetic poles A bar magnet, coil or current loop, if their size is small, create a dipole field The Earth's field, as a crude approximation, also resembles that of a dipole, located near the Earth's center
A speaker which radiates sound primarily in opposite directions, 180 degrees out of phase, This creates a null, or area with no sound, to the sides of the speaker Such designs are engineered by using drivers wired out of phase, or by using both sides of a flat driver
An open-back speaker that radiates sound equally front and rear The front and rear waves are out of phase and cancellation will occur when the wavelengths are long enough to "wrap around" The answer is a large, wide baffle or to enclose the driver creating a monopole
A pair of equal and opposite electrical charges separated by a small distance A dipole will align itself, if possible, in the presence of other electrical charges according to the attraction of opposite and repulsion of like charges Externally electrically neutral chemical molecules can have a dipole inside E g , water is a triangular molecule with the oxygen at one corner and the two hydrogens at the other two corners The internal charge distribution is such that the hydrogen side has a slight excess of positive charge and the oxygen end is correspondingly negative A dipole is characterized by its "dipole moment," the product of the charge and the separation distance (coulomb times centimeter)
an aerial half a wavelength long consisting of two rods connected to a transmission line at the center a pair of equal and opposite electric charges or magnetic poles separated by a small distance
A fundamental form of antenna, comprising a single conductor of length approximately equal to half the wavelength of the carrier wave Provides the basis for a range of other more complex forms of antenna
Two equal electric or magnetic charges of opposite sign, separated by a small distance In the electric case, the dipole moment is given by the product of one charge and the distance of separation This appplies to charge and current distributions as well In the electric case, a displacement of charge distribution produces a dipole moment, as in a molecule
A very common structure of magnetic field lines in nature See the figure Many planets, including Earth, have almost dipolar field lines, at least in the near region the planet The "di-" in dipolar refers to the two poles, north and south The overall structure is symmetric about its axis In Earth's case the directions of all of these field lines change over very long periods of time and in fact, the dipole structure has polarity (sign) changes so that its north and south poles change places on a time-scale of hundreds of thousands of years