Magnetic Field
Direction N → S · Stronger near poles · Weaker with distance.
A magnetic field is the region around a magnet or current-carrying conductor where magnetic effects can be detected, represented by field lines and vectors.
Definition of magnetic field
A magnetic field is a vector field around a magnet, current-carrying conductor, or moving charge in which another magnet or moving charge experiences a force. We represent it by magnetic field lines or arrows. The direction at a point is the direction a north pole would tend to move.
Field strength and distance
For a bar magnet, the magnetic field is strongest near the poles and decreases with distance. Field lines crowd where the field is strong and spread out where it is weak. For a long straight current-carrying conductor, the field strength is approximately proportional to current and inversely proportional to distance from the wire.
How would you use a small compass to map the magnetic field around a bar magnet?