In the left hand rule, forefinger always represents ___

Electrical Engineering MCQ Electrical Machines MCQ
1

In the left hand rule, forefinger always represents

A. voltage.
B. current.
C. magnetic field.
D. direction of force on the conductor.

Show Answer

Answer: C

Share your understanding of this question with the correct explanation.

2

In the left-hand rule, the forefinger always represents the direction of the magnetic field. Therefore, the correct answer is C: “magnetic field.”

Here’s a further explanation:

The left-hand rule is a mnemonic or visualization technique used to determine the relationship between the directions of the magnetic field, current, and force in a conductor. It is the left-handed counterpart to the right-hand rule.

To apply the left-hand rule, you can use your left hand with the thumb, forefinger, and middle finger in specific orientations. Here’s how it works:

  1. Point your left thumb in the direction of the current (conventional current flow, opposite to the actual electron flow).
  2. Extend your left forefinger perpendicular to your thumb.
  3. Extend your left middle finger perpendicular to both your thumb and forefinger.

In this configuration, the left forefinger represents the direction of the magnetic field. The magnetic field lines around a current-carrying conductor form circular loops, and the forefinger aligns with these loops, indicating the direction of the magnetic field.

The other fingers can represent different quantities:

  • The left thumb represents the direction of the current.
  • The left middle finger represents the direction of the force on the conductor when it experiences a magnetic field (given a current flowing through it).

Therefore, in the left-hand rule, the forefinger always represents the direction of the magnetic field.