Exam-style question
Try this first
In the timing diagram for a D flip‑flop, the clock rises at 10 µs and the D input is 1 just before the rise. When does the Q output change?.
- A.Immediately at the clock rise
- B.At 10 µs, after the clock has finished rising
- C.At 20 µs, one clock period later
- D.It never changes
Model answer
What a good answer should say
- Immediately at the clock rise
Explanation
Why this works
Evidence: The diagram shows the clock rising at 10 µs and D=1 at that instant. Interpretation: A D flip‑flop captures the D value on the rising edge.
Implication: Q will adopt the value of D immediately after the edge. Conclusion: The correct answer is that Q changes immediately at the clock rise.
Common mistake
No common mistake is linked to this question yet.