Imagine a current-carrying straight conductor with magnetic field of lines in anti-clockwise direction. Then the direction of current is determined by

The direction of the magnetic field around a straight current-carrying conductor is determined by the Right-Hand Thumb Rule, also known as the right-hand grip rule [1][3][4]. 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 curl in the direction of the magnetic field lines [2]. When the magnetic field lines are observed to be in an anti-clockwise direction, applying this rule indicates that the thumb must be pointing in the upward direction [2]. Fleming's Left-Hand Rule is not used for this purpose; it is instead used to determine the direction of force acting on a conductor placed within an external magnetic field [2][3]. Therefore, for an anti-clockwise field, the current must be flowing upwards as per the Right-Hand Thumb Rule.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 12: Magnetic Effects of Electric Current > 12.2.2 Right-Hand Thumb Rule > p. 199
2. [3] Science , class X (NCERT 2025 ed.) > Chapter 12: Magnetic Effects of Electric Current > What you have learnt > p. 206
3. [4] https://en.wikipedia.org/wiki/Right-hand_rule
4. [2] Science , class X (NCERT 2025 ed.) > Chapter 12: Magnetic Effects of Electric Current > Activity 12.7 > p. 203