人教版八下物理同步教学课件第六章电压电阻2探究串、并联电路电压的规律[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. 基础梳理.知识点睛 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 各部分电路两端的电压之 和 U＝U1＋U2 相等 总电 压 U＝U1＝U2 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 若n个用电器串联，则：U＝U1＋U2＋…＋Un；若n个用电器并联，则：U＝U1＝U2＝…＝Un. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 要点归纳.诱思探究 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 实验探究：探究串联电路电压的规律 1.实验器材：两节干电池、导线若干、开关、不同规格的小灯泡若干、电压表. 2.实验步骤： (1)电路图(如图) Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. (2)分别把电压表并联在如图所示的电路的A、B两点，B、C两点，A、C两点，并记下电压表示数. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. (3)换上另外四只不同规格的小灯泡，重复两次实验. (4)实验记录数据如下： (5)分析实验数据知：A、C两点间的电压总等于A、B间电压和B、C间电压之和. 实验序号 1 2 3 A、B间电压U1/V 1.2 1.0 0.8 B、C间电压U2/V 1.8 2.0 2.2 A、C间电压U/V 3 3 3 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 3.实验结论：串联电路中总电压等于各部分电路两端的电压之和. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 1.连接电路时，开关处于断开状态还是闭合状态？ 提示：断开状态. 2.采用不同规格的小灯泡多次测量的目的是什么？ 提示：(1)对于规格相同的小灯泡，无论串联还是并联，两小灯泡两端电压都相同，无法得出实验结论. (2)避免偶然性，使实验结论具有普遍性. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 3.实验中，如何选择电压表的量程？ 提示：所选量程略大于电源电压且指针偏转角度不要太小. 4.若把电压表串联在电路中，小灯泡是否发光？此时电压表的示数是多少？ 提示：因电压表本身电阻很大，故电路中电流几乎为零，小灯泡几乎不发光，此时电压表的示数近似等于电源电压. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 5.当A、B或B、C之间被短路时，电压