Figure 1-28.Magnetic fields around elements.
Magnetic lines of force are indicated by the letter H and are called H lines. The direction of the
magnetic lines may be determined by use of the left-hand rule for a conductor: If you grasp the conductor
in your left hand with the thumb extended in the direction of the current flow, your fingers will point in
the direction of the magnetic lines of force. In view C of figure 1-28, the direction of current flow is
upward along both halves of the elements (conductors). The lines of magnetic force (flux) form
concentric loops that are perpendicular to the direction of current flow. The arrowheads on the loops
indicate the direction of the field. The left-hand rule is used to determine the direction of the magnetic
field and is illustrated in figure 1-29. If the thumb of the left hand is extended in the direction of current
flow and the fingers clenched, then the rough circles formed by the fingers indicate the direction of the
Figure 1-29.Left-hand rule for conducting elements.