Frequency from period for a sawtooth: A sawtooth waveform has a period of 10 ms. What is its frequency in hertz?
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A10 Hz
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B50 Hz
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C100 Hz
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D1,000 Hz
Answer
Correct Answer: 100 Hz
Explanation
Introduction / Context:Frequency and period are reciprocals for any repetitive waveform, including sawtooth signals used in timing, ramp generators, and sweep circuits. Converting between milliseconds and hertz correctly is a fundamental time–frequency skill for electronics and instrumentation work.
Given Data / Assumptions:
- Sawtooth period T = 10 ms.
- Relation: f = 1 / T.
- Units: 1 ms = 10^-3 s, so 10 ms = 0.01 s.
Concept / Approach:Compute the frequency as the reciprocal of the period after converting to seconds. Maintaining unit consistency avoids order-of-magnitude mistakes that are common when switching between milliseconds and seconds.
Step-by-Step Solution:
Convert period: T = 10 ms = 0.01 s.Compute frequency: f = 1 / T = 1 / 0.01 = 100 Hz.Therefore, the frequency of the sawtooth is 100 Hz.Verification / Alternative check:Check via intuition: A period of 10 ms means 100 cycles occur each second (since 100 * 0.01 s = 1 s). This reaffirms the numerical result without further calculation.
Why Other Options Are Wrong:
- 10 Hz: Would correspond to T = 0.1 s (100 ms), not 10 ms.
- 50 Hz: Would require T = 20 ms.
- 1,000 Hz: Would require T = 1 ms.
Common Pitfalls:
- Forgetting to convert milliseconds to seconds before inversion.
- Inverting and then misplacing the decimal point by a factor of 10.
Final Answer:100 Hz