当今世界,导线就像敦煌壁画上飞天仙女的束体飘带,缠绕在人的四面八方.常用的导线是用铜或铝做的,特别重要的用电设备,甚至要用昂贵的银.钢和铁是导体,又多又便宜.那么,为什么不用钢铁来做导线呢?电阻水在水管中流动形成水流时会受到阻力.同样,电荷在导体中做定向移动形成电流时也会受到阻碍.我们把导体对电流的阻碍作用叫做电阻.在物理学中,用“电阻”这个物理量来表示导体对 In today's world, the wire is like a streamer of flying fairies on the Dunhuang frescoes, wrapped around people in all directions. Commonly used wires are made of copper or aluminum, especially important electrical equipment, and even expensive silver. Is conductor, it is more and less expensive.Why do not use steel to make the wire? Resistance water will be resistance when flowing in the water pipe to form water flow, and also the charge will be hindered by the directional movement in the conductor to form the current.We put The resistance of a conductor to current is called resistance. In physics, the physical quantity of “resistance”