In a positive logic system powered near 5 V, which voltage level commonly represents a HIGH (logic 1) state?
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A0 V
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B+1 V
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C+5 V
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D+9 V
Answer
Correct Answer: +5 V
Explanation
Introduction:Positive logic assigns higher voltages to logic 1 (HIGH) and lower voltages to logic 0 (LOW). In many introductory contexts, examples reference 5 V systems.
Given Data / Assumptions:
- Positive logic convention.
- Nominal supply around 5 V, a common educational reference.
- We seek a typical HIGH level under this convention.
Concept / Approach:In positive logic, logic 1 corresponds to a higher potential. With a 5 V supply, the canonical HIGH level is near +5 V, while 0 V corresponds to LOW. Real devices accept a range (e.g., ≥ 2.0 V for TTL), but +5 V is the archetypal level.
Step-by-Step Solution:
Positive logic: HIGH maps to higher voltage.With VCC ≈ 5 V, an idealized HIGH ≈ +5 V.Match the option stating +5 V.Verification / Alternative check:Thresholds vary by family (TTL/CMOS), but illustrative teaching uses +5 V for HIGH and 0 V for LOW in positive logic with 5 V rails.
Why Other Options Are Wrong:
- 0 V: LOW in positive logic.
- +1 V: Below typical VIH(min); not reliably HIGH.
- +9 V: Exceeds the assumed 5 V system; not representative and may damage inputs.
Common Pitfalls:Confusing positive logic mapping with exact VIH thresholds; the concept is mapping, not the precise datasheet limits.
Final Answer:+5 V