Exam-style question
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What is the duty cycle of a 555 timer astable circuit when R1 = 10 kΩ and R2 = 10 kΩ?.
- A.66.7%
- B.50%
- C.33.3%
- D.75%
Model answer
What a good answer should say
- 66.7%
Explanation
Why this works
Formula: D = (R1+R2)/(R1+2R2). Substitution: R1 = 10 kΩ, R2 = 10 kΩ.
Working: D = (10 kΩ+10 kΩ)/(10 kΩ+2×10 kΩ) = 20 kΩ/30 kΩ = 0.667. Answer: 66.7 %.
Units: %. Conclusion: The output high time is about two‑thirds of the period.
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