Exam-style question
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Which of the following best describes the effect of a clock signal on a flip‑flop?.
- A.It changes output immediately
- B.It samples input at clock edge
- C.It resets output
- D.It increases propagation delay
Model answer
What a good answer should say
- It samples input at clock edge
Explanation
Why this works
Formula/rule: Flip‑flops are edge‑triggered devices that change state only on a clock transition. Substitution: The clock edge (positive or negative) triggers the sampling of the input D.
Working: When the clock edge occurs, the flip‑flop latches the input value and holds it until the next edge. Answer: It samples input at clock edge.
Units/conclusion: The clock signal controls when the flip‑flop updates its output.
Common mistake
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