ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 1
alternation, the average value of the voltage values occurring
during the complete cycle is zero.
j. Effective Value of a Sine Wave. Emax Eavg, Imax and Iavg are
values used in ac measurements. Another value used is the
EFFECTIVE value of ac. This is the value of alternating voltage
or current that will have the same effect on a resistance as a
comparable value of direct voltage or current will have on the
same resistance.
In an earlier discussion, it was stated that when current flows
in a resistance, heat is produced. When direct current flows in
a resistance, the amount of electrical power converted into heat
a maximum value of 1 ampere does not maintain a constant value,
the alternating current will not produce as much heat in the
resistance as will a direct current of 1 ampere.
Figure 66 compares the heating effect of 1 ampere of dc to the
heating effect, of 1 ampere of ac.
FIGURE 66. HEATING EFFECT OF AC AND DC.
Examine figure 66; views A and B, and notice that the heat
(70.7 C) produced by 1 ampere of alternating current (that is,
an ac with a maximum value of 1 ampere) is only 70.7 percent of
the heat (100 C) produced by 1 ampere of direct current.
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