From the motion of the conductor in a magnetic field, we know that when a conductor moves in a magnetic field (perpendicular to the motion of the conductor) an EMF is induced across the ends of the conductor called motional EMF. This conductor acts like a source (battery) because it produces the electric current that flows through the loop or circuit. The electric current that it creates is called induced current.
Read also
- Motional EMF from Faraday’s law | definition, formula derivation
- Lenz’s law – statement, formula, application, and experiments
The direction of this induced current can be determined by using Fleming’s right-hand rule.
In this article, we are interested in determining the direction of induced current in the loop, developed when a conductor attached to the loop moves in a magnetic field. So let’s get started… with the article i.e Fleming’s right-hand rule (for generators).
Fleming’s right-hand rule (for generators)
A British engineer, John Ambrose Fleming invented a rule called Fleming’s right-hand rule. This rule is helpful for determining the direction of induced current in the loop when a conductor attached to the loop moves in a magnetic field. It can also be used to determine the direction of current in a generator’s windings.
According to Faraday’s law of electromagnetic induction, When a conductor such as a wire attached to a circuit moves through a magnetic field, an electric current is induced in the wire. The current in the wire can have two possible directions. Fleming’s right-hand rule gives direction in which the current flows.
What does Fleming’s right-hand rule state?
According to Fleming’s right-hand rule, the thumb, index, and middle finger of the right hand are stretched in such a way that they are mutually perpendicular to each other (at right angles). See figure above. If these stretched fingers are put in the system in such a way that –
- The thumb points the direction of the motion of the conductor relative to the magnetic field.
- The index finger points in the direction of the magnetic field. By convention, it’s the direction from the North to the South magnetic pole.
- Then the middle finger represents the direction of the induced current within the conductor.
Mnemonic for remembering the rule
There are various mnemonics for remembering this rule. Some mnemonics are discussed below.
- Father, Mother, and Children, here bold letter F stand for force (otherwise motion of conductor)(Thumb), the bold letter M stands for magnetic field (index finger), and bold letter C stands for direction of induced current (middle finger).
- “FBI”, F stands for Force (or otherwise motion) (thumb), B for the magnetic field (index finger), and I for current (middle finger).
Frequently Asked Questions – FAQs
State Fleming’s right-hand rule.
Fleming’s Right Hand Rule states that if the thumb, index, and middle finger of the right hand are stretched in such a way that they are mutually perpendicular to each other (at right angles) then the thumb points toward the direction of the magnetic force, the index finger points towards the direction of the magnetic field, and the middle finger points towards the direction of the current.
What is Fleming’s right-hand rule also called?
Fleming’s right hand is also h/a dynamo rule. It gives the direction of induced current produced in a straight conductor moving in a magnetic field.
Who invented the right-hand rule?
A British engineer, John Ambrose Fleming invented a rule called Fleming’s right-hand rule.
Where does Fleming’s right-hand rule use?
It can also be used to determine the direction of current in a generator’s windings.
An equivalent version of Fleming’s right-hand rule is?
An equivalent version of Fleming’s right-hand rule is the left-hand palm rule.
