General Theory of the Electromagnetic Field
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Fig. 1.2. The reference directions to the calculation of fluxes for: a – closed surface; b – open surface; c – manifold open surface. surface bounded by a curve forming several near loops (the case of a helix). The surface is a helical one. We shall recall the generation of a helical surface. Consider a straight-line segment having one end at any point on one axis with which the segment forms a constant angle. Let the segment rotate about the axis, and simultaneously the point representing the end above to move along the axis with segments proportional to the arc of rotation of the segment. The curve described by each point of the segment will be a helix. The surface described by the segment will be a helical surface. In the case of the helical surface, it follows that this flux is, in fact, equal to the sum of fluxes through every loop. The flux corresponding to all loops is referred to as linked flux or flux-linkage. The flux through a single sheet is referred to as flux-turn. Each tube of field lines containing a flux equal to the unit may be associated with a central line of field. This line may be referred to as unit field line or unit flux line. Then, the flux through any surface will be equal to the number representing the algebraic sum (i,e., taking into account the sense of the lines) of the unit field lines that pass through the surface.
1.3. PHYSICAL QUANTITIES. LAWS AND THEOREMS. The characterization of physical states and phenomena is achieved by means of physical quantities. A detailed analysis referring to physical quantities has been made in
