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变压器在交流电路中能够起到传递能量、耦合信号、变换电压、电流及阻抗的作用,高中物理下册对其作了简要的介绍,绘出了原副线圈中的电压与匝数成正比、电流与匝数成反比的结论,然而我们在教学中发现:学生在掌握书本上的这一结论时往往会随便加以推广,例如175页练习四第2题;收音机中的变压器,原线圈有1210匝,接在220伏的电源上,要得到5伏、6.3伏和350伏三种输出电压,求这三个副线圈的匝数,此题在变压器空载时将U_1/U_2=n_1/n_2推广到U_1/U_2=n_1/n_2、U_1/U_4=n_1/n_2,是正确的,但若将三组副线圈接上负载,如图所示,每组副线圈内都有电流,学生随便
Transformers can transfer energy, couple signals, convert voltages, currents, and impedances in AC circuits. They are briefly introduced in the High School Physics book, and the voltage in the original secondary coil is plotted against the number of turns. The current is inversely proportional to the number of turns. However, we found in teaching that students often promote this conclusion when they master the book, for example, 175 pages of exercise 4 problem 2; the transformer in the radio, the original coil has 1210匝 匝 接 匝 接 接 接 接 接 接 接 220 220 220 220 220 220 220 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝 匝It is correct to generalize to U_1/U_2=n_1/n_2, U_1/U_4=n_1/n_2, but if the three sets of sub-coils are connected to the load, as shown in the figure, there is current in each set of sub-coils.