Duty cycle calculation: A pulse waveform has a high time (Ton) of 8 ms and a period (pulse width from start of one pulse to the start of the next) of 32 ms. What is the duty cycle?
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A25%
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B50%
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C1%
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D100%
Answer
Correct Answer: 25%
Explanation
Introduction / Context:Duty cycle quantifies the fraction of time a digital or pulse waveform stays high during each cycle. It is widely used in PWM control, digital timing, and communications. The duty cycle is expressed as a percentage of the period.
Given Data / Assumptions:
- High (on) time Ton = 8 ms.
- Period T = 32 ms (time between successive pulse starts).
- Single, stable repetition rate; ignore rise/fall times.
Concept / Approach:
Duty cycle D is defined as D = (Ton / T) * 100%. Insert the given values directly to compute the percentage.
Step-by-Step Solution:
Write formula: D = (Ton / T) * 100%.Substitute: D = (8 ms / 32 ms) * 100%.Compute: D = 0.25 * 100% = 25%.Verification / Alternative check:
Sanity check: Since the high time is one quarter of the period, the duty cycle must be 25%. The waveform is high for 8 ms and low for 24 ms each 32 ms cycle.
Why Other Options Are Wrong:
50% would require Ton = T/2 = 16 ms. 1% implies Ton ≈ 0.32 ms. 100% means always high (no low time), which is not the case here.
Common Pitfalls:
Confusing 'pulse width' as Ton; here, the problem clarifies the period is 32 ms. Always confirm definitions in context.
Final Answer:
25%