Definition
A memory aid used to determine the direction of induced current flow in a generator. With the thumb, index finger, and middle finger of the left hand held at right angles to one another, the thumb points in the direction of conductor motion, the index finger points in the direction of the magnetic field (north to south), and the middle finger points in the direction of induced current flow.
Plain English
A hand trick that uses the three fingers of your left hand, each pointing in a different direction, to figure out which way electricity will flow in a generator when you know which way the wire is moving and which way the magnetic field is pointing.
Context Anchor
Seen in aircraft electrical-system study, especially when learning how generators produce electrical power.
Derivation
Called the 'left-hand rule' because it uses the left hand specifically. The left hand is used for generators (which produce current); the right hand is used for motors (which consume current). Keeping them on opposite hands prevents mixing them up.
Why Pilots Care
Correct understanding of generator current direction supports accurate troubleshooting of aircraft charging systems and prevents misdiagnosis of polarity or output faults.
Grounding Statement
Picture a wire being pushed through the space between magnet poles; the left-hand rule tells you which way the produced electricity moves.
Intuition Check
This is not a rule about the left side of the airplane or which hand to use on a control. It is a memory aid for matching three directions: magnetic field, wire movement, and electron flow.
Example Sentence 1
The instructor used the left-hand rule for generators to show how the spinning armature produces current in a specific direction.
Example Sentence 2
During systems class the instructor demonstrated how the left-hand rule for generators predicts output polarity when the field and rotation directions are known.