[自制土电话ppt.ppt

* Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 土电话是利用声音振动传播的原理设计的。土电话的制作原理是棉线、铁丝等固体物质能传播声音。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. A．制作方法 ①话筒。找两只一次性纸杯，用剪刀把杯底剪掉。每个纸杯都是既做话筒又做听筒。 ②振动膜。用牛皮纸做振动膜。将纸剪成圆形，比纸杯底直径略大。用胶水将圆贴在杯底，纸尽可能拉紧。 ③穿线。找一根几米长的棉线， 把两个纸杯连起来，用大头针在纸杯振动膜中心穿一小孔，把棉线分别穿入两个纸杯中，并打个结。这样，土电话就做成了。 B．游戏方法 让两个学生，一人拿来一个纸杯，一人把纸杯当话筒，一人把纸杯当听筒。当一人对着话筒小声说话时，声音使振动膜发生振动，通过拉紧的棉线穿到对方的振动膜上，使听筒那边同样的振动，这样声音就传到另一个人了耳朵里去了。 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. 土电话制作时的几个注意点： 第一、在制作过程中，如果纸杯底部穿的孔眼太大，空气就能自由通过，气体传声效果比固体传声效果差，这样会影响土电话的通话效果。 第二、两个纸杯之间的棉线要绷紧。声音是通过震动产生的，所以声音在传播时，也必须通过介质的震动来传播。但是土电话的棉线在不绷紧的情况下，由于它的重力等因素，使它的震动传导性大幅度降低，土电话没有足够的能量使它震动，所以就会听不见声音。 第三、两个纸杯之间的棉线在五米以内，用不用土电话无关紧要，只有在五米以上，土电话才起到应有的作用。 第四、金属丝传声比棉线传声效果好。 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. 做好之后，我们可以互相通话啦！快来试一试吧！ 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.