Definition
In digital electronics, the lower of the two voltage levels used to represent binary states. In a typical positive-logic circuit, logic zero corresponds to the lower voltage (often near 0 volts) and represents the binary value 0, or the 'off' or 'false' state of a logic signal.
Plain English
One of the two voltage levels a digital circuit uses to represent information. Logic zero is the lower voltage and stands for 'off' or '0' in binary.
Context Anchor
Seen in avionics, aircraft electrical system descriptions, and troubleshooting procedures for digital equipment.
Derivation
From 'logic,' meaning the rules a digital circuit follows, and 'zero,' the binary digit it represents. Digital circuits only recognize two states, so engineers labeled the lower voltage 'logic zero' and the higher one 'logic one' to match the binary numbers 0 and 1.
Why Pilots Care
Modern aircraft systems — autopilots, flight management computers, glass cockpits — all run on digital logic. Understanding that signals inside these systems are either logic zero or logic one helps when reading maintenance manuals or troubleshooting avionics behavior.
Analogy
Think of a light switch. Logic zero is the switch in the 'off' position, and logic one is the 'on' position. The circuit only cares which of the two states the switch is in.
Intuition Check
Do not assume logic zero means “nothing is happening.” It means the system is seeing the signal state assigned to the value 0.
Example Sentence 1
When the sensor is inactive, the circuit outputs a logic zero to the flight computer.
Example Sentence 2
A logic zero signal from the module confirmed the sensor detected no fault.