在日常生活和生产实践中,我们知道,银、铜、铁、碳等材料很容易导电,是导体;而橡皮、塑料、陶瓷等材料,对电流的阻力却极大,很不易导电,是绝缘体。另外还有一些材料,如硅、锗等,导电性能介于导体和绝缘体之间,称为半导体。通常我们甩电阻这个物理量来表征物体的导电性能,它指的是电流在物体中遇到的阻 In daily life and production practice, we know that silver, copper, iron, carbon and other materials are easily conductive, is the conductor; and rubber, plastic, ceramic and other materials, the resistance of the current is great, it is not easy to conduct electricity, is the insulator . In addition there are some materials, such as silicon, germanium, etc., between the conductivity of the conductor and insulator, known as the semiconductor. Usually we use the physical quantity of resistance to characterize the conductivity of an object. It refers to the resistance that current encounters in an object