Which statement best describes the right-hand rule for the direction of the magnetic field around a straight current-carrying wire?

Which statement best describes the right-hand rule for the direction of the magnetic field around a straight current-carrying wire?

• A. The magnetic field direction is given by curling the fingers of the right hand when the thumb points in the current direction.
• B. The magnetic field direction points along the wire.
• C. The magnetic field direction is radial outward from the wire.
• D. The magnetic field direction is independent of current direction.

Answer: (A)

The direction of the magnetic field around a straight current-carrying wire is shown by the right-hand rule: when you point your thumb in the direction of the current, the way your fingers wrap around the wire gives the direction of the magnetic field lines. In other words, the field forms circular loops around the wire, not along the wire or radially outward. The sense of those loops depends on the current direction—reverse the current and the field direction reverses. This rule provides a clear mental picture: grasp the wire with your right hand, thumb along the current, and the curled fingers indicate the magnetic field around the wire.

The direction of the magnetic field around a straight current-carrying wire is shown by the right-hand rule: when you point your thumb in the direction of the current, the way your fingers wrap around the wire gives the direction of the magnetic field lines. In other words, the field forms circular loops around the wire, not along the wire or radially outward. The sense of those loops depends on the current direction—reverse the current and the field direction reverses. This rule provides a clear mental picture: grasp the wire with your right hand, thumb along the current, and the curled fingers indicate the magnetic field around the wire.