A current-carrying wire is known to produce magnetic lines of force around the conducting straight wire. The direction of the lines of force may be described by

The direction of magnetic lines of force around a straight current-carrying conductor is determined by the right-hand thumb rule [2]. According to this rule, if you imagine holding the conductor in your right hand with the thumb pointing in the direction of the current, your fingers will wrap around the wire in the direction of the magnetic field lines [1]. This rule is universally applicable regardless of whether the current is flowing upward or downward [2]. For an upward current, the field lines appear counter-clockwise when viewed from above, while for a downward current, they appear clockwise. In both scenarios, the right-hand thumb rule remains the standard method for determining the field's orientation [2]. Fleming's left-hand rule, by contrast, is used to determine the direction of force acting on a conductor in an external magnetic field, not the field produced by the wire itself.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 12: Magnetic Effects of Electric Current > 12.2.2 Right-Hand Thumb Rule > p. 200
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 12: Magnetic Effects of Electric Current > What you have learnt > p. 206