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初三物理有电话的内容,过去对于电话机的构造和原理总是从抽象的理论上讲解,学生感到难以理解,我设计了如下的一个简单实验,效果较好。 1.实验装置 (1)玻璃漏斗一只;(2)毫安表一只;(3)新的干电池2～3节(1号电池);(4)弹簧一支,细线一根;(5)铁架一只;(6)活性碳粒(能刚好装满玻璃漏斗);(7)蹄形电磁铁(线圈用铜线绕400匝);(8)衔铁一块,另外在玻璃漏斗左右用软铁皮包住连接导线4根,按图连接起来,在图中的Ⅰ是话筒部分,Ⅱ是听筒部分。 2.演示过程: 当用拇指压右边软铁皮使碳粒压紧,由于碳粒压紧电路中的电阻变小,因而电流增大,这时从毫安表上
In the third year of physics, there were telephone contents. In the past, the structure and principle of the telephone were always explained in terms of abstract theory. Students felt difficult to understand. I designed the following simple experiment with good results. 1. Experimental apparatus (1) One glass funnel; (2) One milliampere meter; (3) New dry cell 2 to 3 cells (1 cell); (4) One spring, one thin line; 5) One iron frame; (6) Activated carbon particles (can just fill the glass funnel); (7) Hoof-shaped electromagnet (coil is wound with 400 turns of copper wire); (8) One piece of armature and the other around the glass funnel Attach the four connecting wires with a soft iron sheet and connect them as shown in the figure. I in the figure is the microphone part and II is the handset part. 2. Demonstration process: When pressing the right soft iron sheet with the thumb to compact the carbon particles, the current increases due to the smaller resistance in the carbon particles compacting circuit, and then from the milliammeter.