Wireless Telegraphy and Telephony
Forfatter: Alfred P. Morgan
År: 1917
Forlag: The Norman W. Henley Publishing Company
Sted: New York
Udgave: Third Edition, Fully Illustrated
Sider: 33
UDK: 621.396.1 Mor
A practical Treatise on Wireless Telegraphy and Telephony, giving Complete and Detailed Explanations of the Theory and Practice of Modern Radio Apparatus and its Present Day Applications, together with a chapter on the possibilities of its Future Development
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38
WIRELESS TELEGRAPHY
to a maximum and dying away again. This is repeated
a definite number of times per second; when the current
rises from zero, reverses and returns to zero it is said to
have passed through a cycle. From a to c represents a
Fig. 44.—Leyden jar set for oil immersion to prevent losses from
brush discharges.
cycle—from a to b is an alternation. The usual frequency
of commercial alternating currents is 60 cycles or 7200
alternations per minute.
From these facts we may readily see why the trouble-
some interrupter may be eliminated when alternating
current is used. Every time that the current rises and
falls the magnetic field changes.