Longman Dictionary of Contemporary English
The Collaborative International Dictionary
n. (context physics English) a condition in the space around a magnet or electric current in which there is a detectable magnetic force and two magnetic poles are present
A magnetic field is the magnetic effect of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude (or strength); as such it is a vector field. The term is used for two distinct but closely related fields denoted by the symbols and , where is measured in units of amperes per meter (symbol: A·m or A/m) in the SI. is measured in teslas (symbol:T; note that although the symbol is capital T, "tesla" is written in lower case in the SI system) and newtons per meter per ampere (symbol: N·m·A or N/(m·A)) in the SI. is most commonly defined in terms of the Lorentz force it exerts on moving electric charges.
Magnetic fields can be produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin. In special relativity, electric and magnetic fields are two interrelated aspects of a single object, called the electromagnetic tensor; the split of this tensor into electric and magnetic fields depends on the relative velocity of the observer and charge. In quantum physics, the electromagnetic field is quantized and electromagnetic interactions result from the exchange of photons.
In everyday life, magnetic fields are most often encountered as a force created by permanent magnets, which pull on ferromagnetic materials such as iron, cobalt, or nickel, and attract or repel other magnets. Magnetic fields are widely used throughout modern technology, particularly in electrical engineering and electromechanics. The Earth produces its own magnetic field, which is important in navigation, and it shields the Earth's atmosphere from solar wind. Rotating magnetic fields are used in both electric motors and generators. Magnetic forces give information about the charge carriers in a material through the Hall effect. The interaction of magnetic fields in electric devices such as transformers is studied in the discipline of magnetic circuits.
A magnetic field is the physical phenomenon produced by moving electric charges and exhibited by ferrous materials.
Magnetic field or magnetic fields may also refer to:
Usage examples of "magnetic field".
Other examples of lies-to-children are the idea that the Earth's magnetic field is like a huge bar magnet with N and S marked on it, the picture of an atom as a miniature solar system, the idea that a living amoeba is a billion-year-old 'primitive' organism, the image of DNA as the blueprint for a living creature, and the connection between relativity and Einstein's hairstyle (it's the sort of crazy idea that only people with hair like that can come up with).
When that tilted nucleus is put into a magnetic field, the axis of the tilt will change, and the nucleus will also wobble at a certain speed.
In a plasma made up of particles of differing masses such as electrons and protons, a magnetic field will accelerate the masses at different rates, concentrating them into polarized regions of opposite charge.
We would have to build up a magnetic force in our coil that opposed the greater magnetic field and bent the magnetic lines of force away.
From this he deduced the presence of what we now call a magnetic field.
If we follow the same course which led us to start our study of electricity with the primitive process of generating it, we shall turn now to the basic phenomenon produced by a magnetic field already in existence.
There, where the magnetic field of the planetary body was bent inward right down to the ground, the potent Van Allen radiation belt was a minimum threat.
And in the back of my mind was the thought: If they could manipulate the stellar magnetic field, what else could they do that we hadn’.
The field was caused by the terrific surges of current, and that magnetic field caused the walls of the ship to heat up due to the generation of electric current in the walls.
Rapidly Warren eased off the attractive field that had held the fleet helpless, as they one by one fluttered a moment in the re-asserted gravity of the planet, and righted, he released the magnetic field entirely, and the last of the gravity field.