A current through a horizontal power line flows in east to west direction. What will be the direction of magnetic field at a point directly below it when viewed from east end?

Using the right-hand thumb rule: if the thumb points in the direction of current (east to west), the fingers curl in the direction of the magnetic field. For a point directly below the wire, applying the right-hand rule with the thumb pointing west, the magnetic field at the point below points from north to south (towards the south). When viewed from the east end, the field circulates in a clockwise direction in a plane perpendicular to the wire.