Subelement A: Principles— Topic 7: Waveforms
Question 3-7A1
Element 3 (GROL)What is a sine wave?
Explanation
A sine wave is the fundamental waveform of alternating current (AC) and is crucial in radio theory. Option B accurately describes its geometric generation: if you imagine a point rotating uniformly around a circle, its vertical (or horizontal) projection onto an axis over time will trace out a perfect sine wave. This illustrates its smooth, periodic variation in amplitude.
Option A is incorrect because a sine wave's voltage is constantly varying, not constant. Option C is wrong because a sine wave follows the trigonometric sine function, not the tangent function, which has infinite discontinuities. Option D is incorrect; a sine wave's polarity changes in a perfectly predictable and regular manner, not randomly.
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