F

Fleming's Rule

Left-hand rule (motor): F = IL × B; right-hand rule (generator)
Quick Reference
Formula / NotationLeft-hand rule (motor): F = IL × B; right-hand rule (generator)
Also Known AsLeft-hand rule (motor rule), right-hand rule (dynamo rule), Lorentz force direction

What is Fleming's Rule?

Rules devised by John Ambrose Fleming to determine the direction of current, force, or motion in electromagnetic devices. The left-hand rule applies to motors; the right-hand rule applies to generators. Each finger represents force, field, or current directions.

Formula & Notation

Left-hand rule (motor): F = IL × B; right-hand rule (generator)

Other Names / Synonyms: Left-hand rule (motor rule), right-hand rule (dynamo rule), Lorentz force direction

Properties & Characteristics

Fleming's rules (left-hand and right-hand rules) are mnemonic devices for determining the direction of force (motor effect) or current (generator effect) in electromagnetic systems. The left-hand rule: thumb = motion of conductor, index = magnetic field direction, middle finger = current direction (for motors). The right-hand rule applies to generators. They use the cross-product relationship F = IL × B (Lorentz force).

Uses & Applications

Fleming's rules are used in understanding electric motors, generators, and magnetohydrodynamic (MHD) devices. In chemistry, the right-hand rule is used to determine the direction of magnetic flux in NMR spectrometer magnets and in the Hall effect (determining charge carrier sign in semiconductors).

Safety Information

No direct safety concern for the conceptual rules. Electromagnetic devices governed by these rules (motors, generators, MRI machines) have associated electrical, mechanical, and magnetic hazards that require appropriate safety protocols.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Fleming's Rule
Formula Left-hand rule (motor): F = IL × B; right-hand rule (generator)
Synonyms Left-hand rule (motor rule), right-hand rule (dynamo rule), Lorentz force direction

Frequently Asked Questions

Rules devised by John Ambrose Fleming to determine the direction of current, force, or motion in electromagnetic devices. The left-hand rule applies to motors; the right-hand rule applies to generators. Each finger represents force, field, or current directions.

More "F" Terms

View all "F" terms →
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z