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在演示楞次定律时,常用一种可只绕固定轴转动的一端为封闭的轻金属圆环、另一端为开口的圆环的演示器。如图1所示。 一、用这种仪器演示楞次定律时出现了异常现象。 原演示时,用条形磁铁在闭合金属圆环中插进拔出时,仪器发生转动。用条形磁铁在开口金属环中插进拔出时,因开口圆环中无感生电流,没有感生磁场产生,故仪器不发生绕固定轴转动,从而说明楞次定律。 当使用表面磁场为几千高斯的强磁铁在开口金属圆环中插进拔出时,仪器发生了转动,出现了异常现象。原因是强磁铁在开口圆环中插进拔出时,虽然圆环
In the demonstration of Lenz’s law, a demonstrator that can only rotate around a fixed axis and has a light metal ring closed at one end and an open ring at the other end is commonly used. As shown in Figure 1. First, there was an anomaly when using this instrument to demonstrate Lenz’s law. In the original demonstration, the instrument rotated when a bar magnet was inserted into and extracted from a closed metal ring. When a bar-shaped magnet is inserted into and extracted from an open metal ring, no current is induced in the open ring, and no magnetic field is generated. Therefore, the instrument does not rotate around a fixed axis, thereby illustrating Lenz’s law. When a strong magnet with a surface magnetic field of several thousand gauss was inserted in and pulled out of the open metal ring, the instrument turned and an abnormal phenomenon occurred. The reason is that strong magnets are inserted into and pulled out of the open ring, although the ring