人教版八下物理同步教学课件第七章欧姆定律[单元复习课件].ppt

Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 网络构建.图文诠释 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 参考答案：①电流表、电压表、定值电阻、 滑动变阻器、电源、开关、导线 ②当导体 的电阻一定时，导体中的电流和导体两端的 电压成正比 ③导体中的电流，跟导体两端的电压成正比，跟导体的电阻成反比；I=U/R ④串联电路的总电阻的阻值比任何一个分电阻的阻值都大;并联电路的总电阻的阻值比任何一个分电阻的阻值都小 ⑤R=U/I ⑥电流表、电压表、小灯泡、滑动变阻器、电源、开关、导线 ⑦小灯泡的电阻随温度的升高而增大 ⑧正常接通的电路 ⑨没有接通的电路 ⑩电流不经用电器,而把电源直接连接起来 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 精要剖析.典题例证 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 测量电阻的常规方法是“伏安法”，即用电流表、电压表分 别测出待测电阻的电流、电压，然后根据欧姆定律得 求出. 其他的一些测量电阻的方法是 电阻的测量 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 电路图 直接测得的物理量 计算电阻的表达式 方法1 待测电阻两端的电压U和待测电阻中的电流I Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 方法2 待测电阻Rx两端的电压U1和已知电阻R两端的电压U2 方法3 通过待测电阻Rx的电流I1和通过已知电阻R的电流I2 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 方法4 S接a时电路中电流I1；S接b时通过已知电阻R的电流I2 方法5 S接b时已知电阻R两端的电压U2；S接a时的电压表示数U1 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 1.实验室备有下列器材： A.待测定值电阻Rx：阻值在7～9 Ω之间 B.滑动变阻器：最大阻值500 Ω C.滑动变阻器：最大阻值10 Ω