Consider the following statements about magnetic field due to a current-carrying straight conductor:

The direction of the south pole of a compass needle at a point gives the direction of the magnetic field at that point.

The direction of the magnetic field lines gets reversed if the direction of the current in the conductor is reversed.
Which of the above statements is/are correct?

Correct option is D

Sol: The correct answer is (d) Only (b)

Analyze the given statements about the magnetic field due to a current-carrying straight conductor:

• "The direction of the south pole of a compass needle at a point gives the direction of the magnetic field at that point"
  
• The north pole of a compass needle points in the direction of the magnetic field lines, not the south pole.
• The south pole of a compass needle points opposite to the magnetic field direction.
• "The direction of the magnetic field lines gets reversed if the direction of the current in the conductor is reversed"
  

According to Ampere’s Right-Hand Rule or Right-Hand Thumb Rule, if the direction of the current in a conductor is reversed, the direction of the magnetic field lines around it also reverses