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一、电磁感应定律的引出从中学生的可接受能力考虑,我们可以运用实验定性地引出这一定律。实验(一) 连接原线圈与演示电流表成闭合电路。持条形磁铁插入原线圈,此时,电流表指针发生一定的偏转,然后,使两块条形磁铁并用,插入上述原线圈中,且尽力使此次插入线圈所用时间与前次相同,让学生注意观察电流表指针的偏转情况,并启发学生比较两次实验中电流表指针偏转的大小,可见两次实验中产生的感生电流大小不同。设第一次实验时,磁通量的变化是△φ′,第二次用两块磁铁实验时,磁通量的变化为△φ″,显然,△φ″>△φ′。又第二次产生的感生电流较第一次大,这便表明:磁通量发生变化所用时间△t相同时,△φ′越大E越大,由精确的实验得:E与△φ′成正比。
First, the induction of the law of electromagnetic induction Considered from the acceptability of high school students, we can experimentally lead to this law. Experiment (A) Connect the original coil and demo ammeter into a closed circuit. The bar-shaped magnet is inserted into the primary coil. At this point, the ammeter pointer is deflected. Then, the two bar-shaped magnets are used in combination and inserted into the primary coil, and the best time to insert the coil is the same as the previous one, Pay attention to observe the deflection of the ammeter pointer, and inspire students to compare the size of the ammeter pointer deflection in two experiments. It can be seen that the induced currents in the two experiments are different in size. The first experiment, the change in magnetic flux is △ φ ’, the second time the two magnets experiment, the change in magnetic flux △ φ “, obviously, △ φ”> △ φ’. The second induced induced current larger than the first, which shows that: when the magnetic flux changes the same time △ t, △ φ ’the greater the greater the E, from the exact experiment: E and △ φ’ into Is proportional.