Question

In Fleming's left-hand rule, the index finger of the left hand indicates

• A. Direction of magnetic field
• B. Direction of electric force applied on the conductor
• C. Direction of electric current flowing in the conductor
• D. None of these

Hint:

A common mnemonic is FBI: Force (Thumb), B-Field (Index), Current (Middle). 'B' is the symbol for magnetic field density. This helps remember the association for each finger. Remember, Left Hand is for Motors, Right Hand is for Generators.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Fleming's left-hand rule is a mnemonic used to find the direction of the force (or motion) on a current-carrying conductor in a magnetic field. This is the principle behind electric motors.

Step 2: Detailed Explanation:
To use the rule, you orient your left hand so that the thumb, index finger (forefinger), and middle finger are mutually perpendicular to each other.
\[\begin{array}{rl} \bullet & \text{The Thumb represents the direction of the Thrust or Force (Father).} \\ \bullet & \text{The Forefinger (Index finger) represents the direction of the magnetic Field (Mother).} \\ \bullet & \text{The Centre finger (Middle finger) represents the direction of the Current (Child).} \\ \end{array}\] So, the index finger indicates the direction of the magnetic field.

Step 3: Final Answer:
According to Fleming's left-hand rule, the index finger points in the direction of the magnetic field.