Fleming's right-hand rule
Fleming's right-hand rule (for generators) shows the direction of induced current when a conductor moves in a magnetic field. It can be used to determine the direction of current in a generator's windings.
When a conductor such as a wire attached to a circuit moves through a magnetic field, an electric current is induced in the wire due to Faraday's law of induction. The current in the wire can have two possible directions. Fleming's right-hand rule gives which direction the current flows.
- The thumb is pointed in the direction of motion of the conductor.
- The first finger is pointed in the direction of the magnetic field. (north to south)
- Then the second finger represents the direction of the induced or generated current (the direction of the induced current will be the direction of conventional current; from positive to negative).
The bolded letters in the directions above give a mnemonic way to remember the order. Another mnemonic for remembering the rule is the initialism "FBI", standing for Force (or otherwise motion), B the symbol for the magnetic field, and I the symbol for current. The subsequent letters correspond to subsequent fingers, counting from the top. Thumb -> F; First finger -> B; Second finger -> I