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初中物理第二册第十章第五节“研究通电螺线管的磁性”演示实验效果不明显,几乎看不出。笔者在教学中作了如下改进、效果很好。改进方法一。自制一只长而软的弹簧(K值小),这样在弹簧受到较小拉力时刁L也较明显。铁块改为收音机天线磁棒,减轻了悬挂物的自重,用软弹簧成为可能。为了看得清,在磁棒上涂上红白相间的标记。螺线管可用万用变压器的原线圈、也可自绕一个匝数多些的细长线圈,留中心抽头供改变匝数用。
The second chapter of junior high school physics second chapter tenth chapter “ study the energization of the magnetic solenoid ” demonstration experiment is not obvious, almost no see. The author made the following improvements in teaching and the results were very good. One way to improve. Make a long, soft spring (small K) so that the spring is more pronounced when the spring is under less tension. The iron block was changed to a radio antenna magnetic bar, which reduced the weight of the suspension and made it possible to use a soft spring. To see clearly, apply a red and white mark on the magnet. The solenoid can use the original coil of a universal transformer, or it can be self-running around one more turns of an elongated coil, leaving the center tap for changing the number of turns.