Lessons in elementary physics / by Balfour Stewart.

  • Balfour Stewart
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: Lessons in elementary physics / by Balfour Stewart. Source: Wellcome Collection.

    414/502 page 394
    paper gummed on the end of the magnet) crosses the line i i' ruled on a piece of mirror glass placed at the bottom of the box. Let us suppose the time of vibration t has been correctly ascertained at a place where the horizontal magnetic force is H. Let the observation be now repeated at some other locality where the time of vibration is then if h' is now the horizontal intensity, we shall have the following rela- tion— H or the horizontal intensities are inversely as the squares of the times of vibration. 37S. The Moment of a Magnet.—Suppose N S (Fig. 123/1) be a magnet free to move in a uniform field of force of unit N S' Fig. J23/1. strength. If it be deflected out of its position of rest N s to the position n' .s' perpendicular to the lines of force it will have now a tendency to return to its original position, for it is acted upon by two equal and opposite forces each of strength m, where in is tlie strength of each of the poles. In other words, it is under the action of a couple. Now the turning power of a couple is measured by the product of one of the forces by the perpendicular distance between them. In the particular case under consideration tlie moment of the magnetic couple is m /, where / is the distance apart of the poles. It is convenient to
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