Period from cycles over time: If a sine wave completes 10 cycles in 20 µs (microseconds), what is the period of one cycle?
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A2 µs
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B4 µs
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C20 µs
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D100 µs
Answer
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