Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
According to Fleming's Left Hand Rule, if the thumb points in the direction of the force on the conductor, what does the middle finger represent?
Direction of the magnetic field
Direction of the current
Direction of motion of the conductor
Direction of the induced EMF
Direction of the current
Fleming's Left Hand Rule states that the middle finger of the left hand points in the direction of the electric current when the thumb and first two fingers are held mutually perpendicular. In this configuration, the thumb indicates the direction of the force (or motion) on the conductor, and the forefinger indicates the direction of the magnetic field.
Fleming's Left Hand Rule states that the middle finger of the left hand points in the direction of the electric current when the thumb and first two fingers are held mutually perpendicular. In this configuration, the thumb indicates the direction of the force (or motion) on the conductor, and the forefinger indicates the direction of the magnetic field.
Think of a 'three-dimensional coordinate system' using your hand: the forefinger is the X-axis (magnetic field), the middle finger is the Y-axis (current), and the thumb is the Z-axis (thrust/force).
FBI: F (Thumb - Force), B (Forefinger - Magnetic Field), I (Middle finger - Current).
F=I(L├ЧB) тАФ Lorentz force on a current-carrying wire
The rule is a visual representation of the Lorentz force law, where the force F on a current-carrying conductor is given by F=I(L├ЧB). When the current I and magnetic field B are at right angles, the resulting force F is perpendicular to both, as dictated by the cross product. This principle is fundamental to the operation of electric motors which convert electrical energy into mechanical work.
Used specifically for electric motors.
Fingers must be held at 90┬░ (mutually perpendicular) to each other.
If current flows in the opposite direction, the direction of force also reverses.
Provides a simple visual mnemonic for complex electromagnetic interactions.
Helps in predicting the rotation direction of DC motors.
Only applicable when magnetic field and current are at 90┬░.
Easy to confuse with Fleming's Right Hand Rule (used for generators).
Electric motors
Loudspeakers
Galvanometers
The forefinger always points from North to South magnetic pole.
Option C is synonymous with the direction of the force (thumb), making it incorrect as a separate representation for the middle finger.
Option D describes Fleming's Right Hand Rule, which is used for induced current in generators.
B is correct тАФ According to Fleming's Left Hand Rule, the middle finger represents the direction of the electric current.
Always remember: 'Left Hand = Motor (Force), Right Hand = Generator (Current/EMF)'. A common trick in exams is to swap the two rules, so visualize your hand position before selecting.