| an imaginary line or curve in a field of force, as an electric field, such that the direction of the line at any point is that of the force in the field at that point. |
| line of force
A line used to indicate the direction of a field, especially an electric or magnetic field, at various points in space. The tangent of a line of force at each point indicates the orientation of the field at that point. Arrows are usually used to indicate the direction of the force. See Note at magnetism. |
field line
in physics, path followed by an electric charge free to move in an electric field or a mass free to move in a gravitational field, or generally any appropriate test particle in a given force field. More abstractly, lines of force are lines in any such force field the tangent of which at any point gives the field direction at that point and the density of which gives the magnitude of the field. The concept of lines of force was introduced into physics in the 1830s by the English scientist Michael Faraday, who considered magnetic and electric effects in the region around a magnet or electric charge as a property of the region rather than an effect taking place at a distance from a cause
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