A freely suspended magnet points nearly north and south.

A magnet has two main points of attraction called respectively the
north and south poles.

[Illustration: FIG. 223.--The magnetic needle.]

306. The Extent of Magnetic Attraction. If a thin sheet of paper or
cardboard is laid over a strong, bar-shaped magnet and iron filings
are then gently strewn on the paper, the filings clearly indicate the
position of the magnet beneath, and if the cardboard is gently tapped,
the filings arrange themselves as shown in Figure 224. If the paper is
held some distance above the magnet, the influence on the filings is
less definite, and finally, if the paper is held very far away, the
filings do not respond at all, but lie on the cardboard as dropped.

The magnetic power of a magnet, while not confined to the magnet
itself, does not extend indefinitely into the surrounding region; the
influence is strong near the magnet, but at a distance becomes so weak
as to be inappreciable. The region around a magnet through which its
magnetic force is felt is called the field of force, or simply the
magnetic field, and the definite lines in which the filings arrange
themselves are called lines of force.

[Illustration: FIG. 224.--Iron filings scattered over a magnet arrange
themselves in definite lines.]

The magnetic power of a magnet is not limited to the magnet, but
extends to a considerable distance in all directions.