第1页共189页初中物理衡水中学★内部绝密资料（贝壳课堂）第2页共189页目录第一章声现象·································3第二章光现象·································7第三章透镜及其应用···························9第四章物态变化·······························17第五章电流和电路·····························21第六章电压电阻·····························26第七章欧姆定律·······························30第八章电功率·································35第九章电与磁·································40电学部分综合训练·······················45第十章多彩的物质世界························53第十一章运动和力·····························58第十二章力和机械能···························66第十三章压强和浮力···························73第十四章机械能·······························82力学部分综合训练·····················90第十五章热和能·······························93第一章声现象一、知识点总结衡水中学★内部绝密资料（贝壳课堂）第3页共189页(一)声音的发生与传播1、一切发声的物体都在振动。用手按住发音的音叉，发音也停止，该现象说明振动停止发声也停止。振动的物体叫声源。2、声音的传播需要介质，真空不能传声。在空气中，声音以看不见的声波来传播，声波到达人耳，引起鼓膜振动，人就听到声音。3、声音在介质中的传播速度简称声速。一般情况下，v固>v液>v气声音在15℃空气中的传播速度是340m/s合1224km/h，在真空中的传播速度为0m/s。4、回声是由于声音在传播过程中遇到障碍物被反射回来而形成的。如果回声到达人耳比原声晚0.1s以上人耳能把回声跟原声区分开来，此时障碍物到听者的距离至少为17m。在屋子里谈话比在旷野里听起来响亮，原因是屋子空间比较小造成...
