According to Biot–Savart law, the direction of the magnetic field due to a current element is determined by which rule?

According to Biot–Savart law, the direction of the magnetic field due to a current element is determined by which rule?

• A. Left-Hand Rule
• B. Right-Hand Rule
• C. Fleming's Left-Hand Rule
• D. Fleming's Right-Hand Rule

Answer: (B)

Biot–Savart assigns the direction of the magnetic field to the current element through a cross product: dB is in the direction of dl × r̂. The right-hand rule is the way to visualize that cross product: point your right thumb along the current element (the direction of dl), and the direction your fingers curl gives the magnetic field lines around the element. For a straight wire, this means the magnetic field forms circles around the wire, with the sense of circulation set by the right-hand rule. This rule is the standard mnemonic for the direction produced by Biot–Savart, reflecting the vector nature of the law. Fleming’s rules describe forces on conductors or induced currents in different situations, so they’re not used to determine the magnetic field direction from a current element.

Biot–Savart assigns the direction of the magnetic field to the current element through a cross product: dB is in the direction of dl × r̂. The right-hand rule is the way to visualize that cross product: point your right thumb along the current element (the direction of dl), and the direction your fingers curl gives the magnetic field lines around the element. For a straight wire, this means the magnetic field forms circles around the wire, with the sense of circulation set by the right-hand rule. This rule is the standard mnemonic for the direction produced by Biot–Savart, reflecting the vector nature of the law. Fleming’s rules describe forces on conductors or induced currents in different situations, so they’re not used to determine the magnetic field direction from a current element.