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在一次教研会上,我听到几位老师说“初中物理上第二册电磁铁一节中,通电螺线管的磁性强弱跟哪些因素有关的实验不好演示”。照书上那样做,实验效果不明显,用肉眼观察不到弹簧的伸长;如果把铁片靠近螺线管,则会一下子把铁片吸下去,但螺线管磁性强弱与电流大小有关这点就没法演示出来了。
At a teaching and research meeting, I heard several teachers say, “What are the factors related to the magnetic strength of the energized solenoid in the second-phase electromagnet of the junior high school physics department?” According to the book, the effect of the experiment is not obvious, and the extension of the spring is not observed with the naked eye; if the iron piece is close to the solenoid, the iron piece will be sucked down at once, but the magnetic strength of the solenoid and the current size There is no way to demonstrate this.