State two properties of magnetic lines of force around a straight conductor carrying current.

Properties of magnetic lines of force around a straight conductor carrying current are following :

1. The magnetic field lines form the concentric circles around the wire, with their plane perpendicular to the straight wire and with their centres lying on the wire.
2. On increasing current in the wire, the magnetic field lines become denser and the iron filings get arranged in circles up to a larger distance from the wire, showing that the magnetic field strength has increased and it is effective up to а larger distance.