State the rule to determine the direction of a

magnetic field produced around a straight conductor carrying current.

The direction of the magnetic field from a current carrying conductor is given by the Right-hand thumb rule. Explanation: According to Right-hand thumb rule:-

When we place our right hand's thumb in the direction of the current and as we wrap our finger around the current carrying conductor.

Wrapped finger will show the direction of the magnetic field.

It is noticeable that the wrapped finger from a closed loop which is also the most important property of the magnetic field.