Deep Dive: E7A11
The correct answer is B: High voltage represents a 1, low voltage a 0. What does 'positive logic' mean in reference to logic devices is that high voltage represents a 1, low voltage a 0. Positive logic uses high voltage for logic 1. For amateur radio operators, this is important for digital circuits. Understanding this helps when working with logic.
Why Other Answers Are Wrong
Option A: Incorrect. Logic devices having high noise immunity isn't positive logic - positive logic is high voltage = 1. Noise immunity isn't the definition. Option C: Incorrect. Logic circuit being in 'true' condition isn't positive logic - positive logic is high voltage = 1. True condition isn't the definition. Option D: Incorrect. 1s and 0s defined as different positive voltage levels isn't correct - positive logic is high = 1, low = 0. Different positive levels isn't correct.
Exam Tip
Positive logic = high voltage represents 1, low voltage represents 0. Think 'P'ositive 'L'ogic = 'P'ositive voltage = '1'. Positive logic uses high voltage for logic 1. Not noise immunity, not true condition, not different positive levels - just high = 1, low = 0.
Memory Aid
Positive logic = high voltage represents 1, low voltage represents 0. Think 'P'ositive 'L'ogic = 'H'igh = '1'. Positive logic uses high voltage for logic 1. Important for digital circuits.
Real-World Example
Positive logic in reference to logic devices: It means high voltage represents a 1, low voltage a 0. For example, +5V = 1, 0V = 0. This is what positive logic means - high = 1, low = 0.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E7A
Reference: 2024-2028 Question Pool · E7 - Practical Circuits
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E7A topic.