- 2074 Bhadra · 3 marks
Fleming's right and left hand rules
Short answer
Fleming's right-hand rule (generator): thumb=motion, forefinger=field, middle=induced emf. Left-hand rule (motor): thumb=force, forefinger=field, middle=current. Both give orthogonal directions of motion, field, and current/emf.
Explain Fleming's right and left hand rules.
Fleming's rules give the directions of the three quantities involved in generator and motor action. Hold the thumb, forefinger and middle finger of the hand at right angles to each other.
| Fleming's right-hand rule | Fleming's left-hand rule | |
|---|---|---|
| Used for | Generators (induced emf) | Motors (force on a conductor) |
| Thumb | Direction of motion of the conductor | Direction of motion (force) on the conductor |
| Forefinger | Direction of the magnetic field (N to S) | Direction of the magnetic field (N to S) |
| Middle finger | Direction of induced emf / current | Direction of current in the conductor |
| Principle | Electromagnetic induction (e = Blv) | Force on a current-carrying conductor (F = BIl) |
Memory aid: the Forefinger is the Field, the middle finger is the Current (or emf), and the thuMb is the Motion (or thrust).
Example: a conductor moves upward in a field pointing from left to right (N on the left). The right-hand rule gives an induced current flowing into the page. Applying the left-hand rule to this current gives a force on the conductor acting downward, which opposes its motion, as Lenz's law requires.
✓ Answer checked by Claude Opus 5.5 (high effort)
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