For a periodic digital waveform, the HIGH time is measured in which units?

Introduction / Context:
Timing metrics are fundamental in digital electronics. A waveform’s HIGH time describes how long the signal remains at the logic-HIGH level during each period. Selecting the correct units reinforces the distinction between time and frequency quantities.

Given Data / Assumptions:

• A periodic digital signal with defined HIGH level and LOW level durations.
• Standard definitions: period T, frequency f, pulse width t_w (HIGH time for a positive pulse).

Concept / Approach:
The HIGH time is a duration. Durations are measured in time units such as seconds, milliseconds, or microseconds. Frequency (hertz) measures how often events repeat per second and is the reciprocal of period. Percent (%) indicates a ratio (duty cycle), not a time quantity by itself.

Step-by-Step Solution:
1) Identify what “HIGH time” means: duration of logic-HIGH level within one cycle.2) Duration implies time units → seconds (or scaled units ms, µs, ns).3) Recognize that hertz is cycles per second, not a duration.4) Duty cycle is a percentage, not a time measure.5) Therefore, the correct unit is seconds.

Verification / Alternative check:
Formula check: duty cycle D = t_high / T. Here t_high must be in seconds to be compatible with period T in seconds. This confirms that HIGH time is a time quantity.

Why Other Options Are Wrong:
Hertz: a rate (1/s), not a time.Cycles: dimensionless count, not a duration.%: a ratio; you still need t_high in seconds to compute D.Volt-seconds: used in magnetics, not appropriate for HIGH time units.

Common Pitfalls:
Mixing up duty cycle (%) with pulse width. Also, confusing frequency with time due to their inverse relationship; they carry different units and meanings.

Final Answer:
Seconds (time units)