ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 1
k. Sine Waves in Phase. When a sine wave is applied to a
resistance, the resulting current is also a sine wave. This
follows Ohm's law which states that current is directly
proportional to the applied voltage. Now examine figure 68.
Notice that the sine wave of voltage and the resulting sine wave
of (current are superimposed on the same time axis. Notice also
that as the voltage increases in a positive direction, the
current increases along with it, and that when the voltage
reverses direction, the current also reverses direction. When
two sine waves, such as those represented in figure 68, are
precisely in step with one another, they are said to be IN
PHASE. To be in phase, the two sine waves must go through their
maximum and minimum points at the same time and in the same
direction.
FIGURE 68. VOLTAGE AND CURRENT WAVES IN PHASE.
In some circuits, several sine waves can be in phase with each
other. Thus, it is possible to have two or more voltage drops
in phase with each other and also be in phase with the circuit
current.
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