ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 1
(c) The ratio of the coil length to the coil width.
(d) The type of material in the core.
(3) Losses in an Electromagnetic Field. When current flows in
a conductor, the atoms in the conductor all line up in a
definite direction, producing a magnetic field. When the
direction of the current changes, the direction of the atoms'
alignment also changes, causing the magnetic field to change
direction. To reverse all the atoms requires that power be
expended, and this power is lost. This loss of power (in the
form of heat) is called HYSTERESIS LOSS. Hysteresis loss is
common to all ac equipment; however, it causes few problems
except in motors, generators, and transformers.
g. Basic AC Generation. From the previous discussion, it was
learned that a currentcarrying conductor produces a magnetic
field around itself, and that a changing magnetic field produces
an emf in a conductor. That is, if a conductor is placed in a
magnetic field, and either the field or the conductor moves, an
emf is induced in the conductor. This effect is called
electromagnetic induction.
(1) Cycle. Figures 58 and 59 on the following two pages show
a suspended loop of wire (conductor) being rotated (moved) in a
clockwise direction through the magnetic field between the poles
of a permanent magnet. For ease of explanation, the loop has
been divided into a dark half and a light half. Notice in view
A of the figures that the dark half is moving along (parallel
to) the lines of force. Consequently, it is cutting NO lines of
force. The same is true of the light half, which is moving in
the opposite direction. Since the conductors are cutting no
lines of force, no emf is induced. As the loop rotates toward
the position shown in figure 59, view B, on the previous page,
it. cuts more and more lines of force per second (inducing ail
ever increasing voltage) because : it is more directly across
the field (lines of force). At figure 59, view B, the conductor
is shown completing onequarter of a complete revolution, or
90, of a complete circle. Because the conductor is now
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