Most iron bars and rails, as the vertical bars of windows, that have stood for a considerable time in a perpendicular position, will be found to be magnetic.
If we suspend a bar of soft iron sufficiently long in the air, will it assume magnetic properties?
It will gradually become magnetic; and although when it is first suspended it points indifferently in any direction, it will at last point north and south.
How may a bar of iron, such as a kitchen poker, be made immediately magnetic, without resorting to the use of other magnets?
If the bar devoid of magnetism is placed with one end on the ground, slightly inclined towards the north, and then struck one smart blow with a hammer upon the upper end, it will immediately acquire polarity, and exhibit the attractive and repellant properties of a magnet.
What is a horseshoe magnet?
It is a magnetic bar bent into the form of a horseshoe.
When a piece of iron not magnetic is brought in contact with a common magnet, it will be attracted by either pole; but the most powerful attraction takes place when both poles can be applied to the surface of the piece of iron at once. The magnetic bars are for this purpose bent into the shape of the letter U, and are termed horseshoe magnets. Several of these are frequently joined together with their similar poles in contact; they then constitute a magnetic battery, and are very powerful, either for lifting weights, or charging other magnets.
If we break a magnet across the middle, what happens?