Imagine a current-carrying wire with the direction of current downward or into the page. The direction of magnetic field lines is

The direction of the magnetic field around a straight current-carrying wire is determined by the Right-Hand Thumb Rule. According to this rule, if you point your right thumb in the direction of the conventional current, your fingers curl in the direction of the magnetic field lines. When the current is directed downward or 'into the page,' the thumb points away from the observer. Consequently, the fingers curl in a clockwise direction around the conductor. This creates a pattern of concentric circles perpendicular to the wire. Conversely, if the current were flowing upward or 'out of the page,' the magnetic field lines would be oriented anti-clockwise. Therefore, for a downward current, the magnetic field lines are clockwise.