電磁作用に関する生徒実験用磁石

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The purpose of this study is to seek the magnets suitable for students' experiment on "the force of a magnetic field on a current-carring conductor".
The main apparatus used in this work is a handmade ampere balance. The investigated magnets are as follows : Fe U-type permanent magnets, Al-Ni-Co U and bar-type permanent magnet, handmade U-type electromagnet and Helmholtz coils.
The results are summarized as follows : 1) A weak magnet does not keep a linear relation between the force and the current because the magnet is magnetized by the current and so the magnetic flux changes into a larger or a smaller density. 2) An expected effect was brought out by a magnet constructed with two iron bar pieces as each pole and from one to four Al-Ni-Co bar permanent magnets as magneto-motive-forces. 3) The non-core electromagnets were suitable one.