ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 1
continuously circulate through the magnet and not leak off into
space.
When bar magnets are stored, the same principle must. he
remembered. Therefore, bar magnets should always be stored in
pairs with a north pole and a south pole placed together. This
provides a complete path for the magnetic flux without flux
leakage.
3. Inductance
The study of inductance presents a very challenging but
rewarding segment of electricity. It is challenging, in the
sense that new concepts are being introduced. The study of
inductance is rewarding in the sense that a thorough
understanding of it will. enable the student to acquire a
working knowledge of electrical circuits more rapidly.
a. Characteristics of Inductance. Inductance is the
characteristic of an electrical circuit that opposes the
starting, stopping, or changing of current . The above
statement is of such importance to the study of inductance that
it bears repeating. Inductance is the characteristic of an
electrical conductor that OPPOSES A CHANGE IN CURRENT. The
symbol for inductance is L, and the basic unit of inductance is
the HENRY (H). One Henry is equal to the inductance required to
induce one volt in an inductor by a change of current of one
ampere per second.
One does not have to look far to find a physical analogy of
inductance. Anyone who has ever had to push a heavy load
(wheelbarrow, car, etc.) is aware that it takes more work to
start the load moving than it does to keep it, moving. Once the
load is moving, it; is easier to keep the load moving than to
stop it again. This is because the load possesses the property
of INERTIA. Inertia is the characteristic of mass which opposes
a CHANGE in velocity. Inductance has the same effect on
current: in an electrical circuit as inertia has on the movement
of a mechanical object. It requires more energy to start or
stop the current than it does to keep it flowing.
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