Which statement correctly describes the left-hand rule for determining the magnetic field around a current-carrying conductor?

Which statement correctly describes the left-hand rule for determining the magnetic field around a current-carrying conductor?

• A. The thumb points in the direction of electron current; the fingers show the field direction.
• B. It is the right-hand rule that applies here.
• C. The magnetic field is unrelated to hand orientation.
• D. The palm indicates the magnetic direction.

Answer: (A)

When you determine the direction of the magnetic field around a current-carrying conductor, you use a hand-rule that links the current direction to the field lines wrapping around the wire. If the flow is due to electrons, the left hand is used: point the thumb along the direction of electron flow, and the curling of the fingers shows the direction the magnetic field forms around the wire. This matches how the field lines circle the conductor and reflects the fact that electrons move opposite to conventional current. So this option is best because it correctly ties the left-hand rule to electron flow and uses the fingers to indicate the magnetic field direction around the conductor. The right-hand rule is the counterpart for conventional current, not this left-hand version; and describing the field as unrelated or pointing with the palm isn’t how we determine the field direction.

When you determine the direction of the magnetic field around a current-carrying conductor, you use a hand-rule that links the current direction to the field lines wrapping around the wire. If the flow is due to electrons, the left hand is used: point the thumb along the direction of electron flow, and the curling of the fingers shows the direction the magnetic field forms around the wire. This matches how the field lines circle the conductor and reflects the fact that electrons move opposite to conventional current.

So this option is best because it correctly ties the left-hand rule to electron flow and uses the fingers to indicate the magnetic field direction around the conductor. The right-hand rule is the counterpart for conventional current, not this left-hand version; and describing the field as unrelated or pointing with the palm isn’t how we determine the field direction.