Period from cycles over time: If a sine wave completes 10 cycles in 20 µs (microseconds), what is the period of one cycle?

Difficulty: Easy

Correct Answer: 2 µs

Explanation:


Introduction / Context:
Period and frequency calculations often start from counts of cycles over a measured time window. Converting counts to per-cycle period is straightforward division, but unit care (microseconds, milliseconds) matters to avoid scale errors.


Given Data / Assumptions:

  • Total time window Δt = 20 µs.
  • Number of cycles N = 10.
  • Uniform sinusoid over the interval (no frequency drift).


Concept / Approach:

The period T is the time per cycle: T = Δt / N. Insert the given total time and the number of cycles completed.


Step-by-Step Solution:

Compute: T = 20 µs / 10 = 2 µs per cycle.Report in microseconds: T = 2 µs.Optionally, frequency f = 1 / T = 1 / (2 µs) = 500 kHz (for context).


Verification / Alternative check:

If each cycle is 2 µs, then 10 cycles take 20 µs, consistent. The reciprocal frequency calculation corroborates the period.


Why Other Options Are Wrong:

4 µs would yield only 5 cycles in 20 µs. 20 µs implies one cycle only. 100 µs is unrelated and would correspond to much lower frequency.


Common Pitfalls:

Dividing the wrong way (N/Δt); mixing µs with ms or s; failing to reduce fraction correctly.


Final Answer:

2 µs

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