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In Fleming's left hand rule, which physical quantity is represented by the middle finger?
Direction of the magnetic field
Direction of electric current
Direction of force
Direction of the motion of conductor
Direction of electric current
In Fleming's left-hand rule, the thumb represents the direction of force (or motion) experienced by the conductor, the forefinger (index finger) represents the direction of the magnetic field, and the middle finger represents the direction of electric current.
In Fleming's left-hand rule, the thumb represents the direction of force (or motion) experienced by the conductor, the forefinger (index finger) represents the direction of the magnetic field, and the middle finger represents the direction of electric current.
Think of it like an electric motor where electrical energy is converted into mechanical motion; the current and magnetic field interact to produce a push (force) in a specific direction.
FBI rule: Thumb = Force, Forefinger = Magnetic field, Middle finger = Current (or father, mother, child for Force, Magnetic field, Current).
F=I(l├ЧB) тАФ Magnetic force on a current-carrying conductor
F=q(v├ЧB) тАФ Lorentz force on a moving charge
When a current-carrying conductor is placed in an external magnetic field, it experiences a force perpendicular to both the magnetic field and the current (Lorentz force). Fleming's left-hand rule provides a visual memory aid to determine this direction: stretch the thumb, forefinger, and middle finger of your left hand mutually perpendicular to each other such that the forefinger points in the direction of the magnetic field and the middle finger points in the direction of the current, then the thumb will point in the direction of the magnetic force.
Fleming's Left-Hand Rule is used for electric motors where magnetic field and current produce a mechanical force.
Thumb = Force (F), Forefinger = Magnetic Field (B), Middle Finger = Current (I).
All three fingers must be held at right angles (90┬░) to each other.
Fleming's Right-Hand Rule is used for generators (motion producing current).
Provides a quick, intuitive visual method to determine the direction of force in electromagnetic devices without complex cross-product vector calculations.
Applicable only when the magnetic field, current, and force are mutually perpendicular.
Working principle of DC motors
Moving-coil galvanometer
Electromagnetic actuators and loudspeakers
Option A (Direction of the magnetic field) is represented by the forefinger.
Option B (Direction of electric current) is represented by the middle finger.
Option C and D (Direction of force / motion of conductor) are represented by the thumb.
B is correct тАФ In Fleming's left-hand rule, the middle finger represents the direction of electric current.
Do not confuse Fleming's Left-Hand Rule (used for Motors: Current input тЖТ Force output) with Fleming's Right-Hand Rule (used for Generators: Motion input тЖТ Current output).
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