________________________________________________________________Wave Propagation
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, illustrated in figure
1-29, is used to determine the direction of the magnetic field. The direction of
the magnetic lines may be determined as follows: If you grasp the conductor
in your left hand with the thumb extended in the direction of the current
flow, then the rough circles formed by the fingers indicate the direction of the
magnetic field.
Figure 1-29. Left-Hand Rule for Conducting Elements
Combined Electric and Magnetic Fields
1-131. The generator, shown in figure 1-30, provides the voltage, which
creates an electric field, and current, which creates a magnetic field. This
source voltage and current build up to maximum values in one direction
during one half-cycle, and then build up to maximum values in the other
direction during the next half-cycle. Both the electric and magnetic fields
alternate from minimum through maximum values in synchronization with
the changing voltage and current. The electric and magnetic fields reach their
maximum intensity one quarter-cycle apart. These fields form the induction
field. Because the current and voltage that produce these E and H fields are
90 degrees out of phase, the fields will also be 90 degrees out of phase.
1-39
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