Which right-hand rule determines the direction of the magnetic field around a straight current-carrying wire?

• A. First right hand rule
• B. Third right hand rule
• C. Second right hand rule
• D. Fleming's left-hand rule

Answer: (C)

The magnetic field around a long straight current carries direction that wraps around the wire in circles. The second right-hand rule gives you this direction directly: point your thumb along the direction of the current, and let your fingers naturally wrap around the wire. The way your fingers curl shows the direction of the magnetic field lines around the wire. So, if the current goes upward, the field circles counterclockwise when viewed from above; if the current goes downward, it circles clockwise. This rule is specifically about the surrounding magnetic field, whereas other rules describe forces on a current in a magnetic field, not the field’s direction itself.