Which equation correctly expresses pulse duration?

Which equation correctly expresses pulse duration?

• A. Pulse duration (μs) = # of cycles × period (μs)
• B. Pulse duration (μs) = # of cycles × period (μs) or Pulse duration (μs) = # of cycles / Frequency (MHz)
• C. Pulse duration (μs) = # of cycles / Frequency (MHz)
• D. Pulse duration (μs) = # of cycles + period (μs)

Answer: (B)

Pulse duration is the total time the pulse lasts, which comes from how many cycles it contains and how long each cycle lasts. If there are N cycles and each cycle has a period T, the duration is N × T. Using frequency, the period is T = 1/f, so duration = N × (1/f). When frequency is in MHz and duration in microseconds, that becomes N ÷ f (in MHz). So the duration can be written as either the number of cycles times the period (μs) or the number of cycles divided by the frequency (MHz). This covers both ways to compute the pulse length, while other forms don’t match the fundamental relationship.

Pulse duration is the total time the pulse lasts, which comes from how many cycles it contains and how long each cycle lasts. If there are N cycles and each cycle has a period T, the duration is N × T. Using frequency, the period is T = 1/f, so duration = N × (1/f). When frequency is in MHz and duration in microseconds, that becomes N ÷ f (in MHz). So the duration can be written as either the number of cycles times the period (μs) or the number of cycles divided by the frequency (MHz). This covers both ways to compute the pulse length, while other forms don’t match the fundamental relationship.