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In Fleming's Left-Hand Rule, what does the index finger represent?
Force
Magnetic Field
Current
Velocity
Magnetic Field
In Fleming's Left-Hand Rule, the index finger represents the direction of the magnetic field. This rule is a visual mnemonic used to determine the direction of force experienced by a current-carrying conductor placed in a magnetic field.
In Fleming's Left-Hand Rule, the index finger represents the direction of the magnetic field. This rule is a visual mnemonic used to determine the direction of force experienced by a current-carrying conductor placed in a magnetic field.
Think of pointing your index finger towards the magnetic field lines like pointing a finger straight ahead, while your middle finger represents the flow of traffic (current); your thumb naturally points sideways in the direction the object gets pushed.
FBI: Thumb = Force, First finger (Index) = Magnetic field, Second finger (Middle) = Current.
F=I(L├ЧB) тАФ Magnetic force on a current-carrying conductor
F=q(v├ЧB) тАФ Magnetic component of the Lorentz force
When a current flows through a conductor situated in an external magnetic field, it experiences a mechanical force governed by the Lorentz force equation. By aligning the mutually perpendicular thumb, index finger, and middle finger of the left hand with the force, field, and current respectively, one can easily deduce the orientation of motion.
The thumb points in the direction of the Force (Motion).
The index finger points in the direction of the Magnetic Field (from North to South).
The middle finger points in the direction of the conventional Current.
The three fingers must be held at right angles (mutually perpendicular) to each other.
Provides a simple, rapid graphical method to determine vector directions in electromagnetic devices.
Only applicable when vectors are mutually perpendicular or evaluated along specific vector components.
Working principle of DC electric motors
Moving-coil galvanometers and actuators
Loudspeakers and magnetic suspension systems
| Feature | Left-Hand Rule | Right-Hand Rule |
|---|---|---|
Primary Application | Electric Motors (finding Force) | Electric Generators (finding Induced Current) |
Thumb Representation | Force / Motion | Motion of Conductor |
Fleming's Left-Hand Rule is fundamentally a consequence of the cross product in the magnetic Lorentz force equation.
Option A represents the thumb, Option C represents the middle finger, and Option D relates to charge velocity.
B is correct тАФ The index finger in Fleming's Left-Hand Rule represents the direction of the magnetic field.
Never mix up the two rules: use Fleming's Left-Hand Rule for Motors (Force) and Fleming's Right-Hand Rule for Generators (Current).
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