The Attractive Power of a Magnet
Magnets and Currents
The magnet best known to us all is the compass needle, but for convenience we will use a magnetic needle in the shape of a bar larger and stronger than that employed in the compass. If we lay such a magnet on a pile of iron filings, it will be found on lifting the magnet that the filings cling to the ends in tufts, but leave it almost bare in the center. The points of attraction at the two ends are called the poles of the magnet.
If a delicately made magnet is suspended as in Figure, and is allowed to swing freely, it will always assume a definite north and south position. The pole which points north when the needle is suspended is called the north pole and is marked N
, while the pole which points south when the needle is suspended is called the south pole and is marked S
A freely suspended magnet points nearly north and south.
A magnet has two main points of attraction called respectively the north and south poles.
FIG. - A magnet.
FIG. - The magnetic needle.