Which waveform type is defined by abrupt transitions between high and low levels?

• A. Sine Waves
• B. Square Waves
• C. Triangular Waves
• D. Sawtooth Waves

Answer: (B)

Abrupt transitions between high and low levels describe a square wave. In an ideal square wave, the signal jumps instantly from the high level to the low level and back again at each edge, producing almost vertical edges. This is what makes it a perfect two-level, binary-like waveform.

Sine waves change smoothly, with no sharp jumps, following a curved path. Triangular waves rise and fall with constant slope, so the transitions are linear rather than vertical. Sawtooth waves have a sharp edge at only one point in each cycle, then ramp continuously in the opposite direction, so there isn’t a pair of instantaneous high-to-low and low-to-high transitions each cycle.

Because it features two abrupt transitions per cycle between the two levels, the square wave best matches the description. Real-world edges aren’t perfectly instantaneous due to finite rise and fall times, but the square wave approximation has those two sharp transitions as the defining trait.