利用楞次定律可以判断各种情况下感生电流的方向。有关楞次定律的演示器有多种多样,但各有其优缺点,本文介绍一种经过改进了的演示器,其结构简单、易于自制、花费甚少、效果明显。一、构造如图1所示,在一个非铁质的架台上端的横梁上,插装两根平行的木质细棒,细棒所决定的平面与桌面平行,在两棒上各扎有四条细绳,中间的两组细绳用以悬挂条形磁铁M,两端的两组用以悬挂两个轻质的铝环A和B。A环是闭合的,B环是断开的(有 Using Lenz’s law can determine the direction of induced current in various situations. There are many kinds of demonstrators about Lenz’s law, but each has its own advantages and disadvantages. This article introduces an improved demonstrator, which has a simple structure, is easy to make, has little cost, and has obvious effects. First, the structure shown in Figure 1, in a non-ferrous frame on the top of the beam, insert two parallel wooden thin rods, the plane determined by the thin rod and the desktop parallel, in the four rods on each bar with four fine In the middle of the ropes, two sets of cords are used to suspend the bar magnets M. Two sets of two ends are used to suspend two lightweight aluminum rings A and B. A ring is closed, B ring is broken (there are