推荐回答(1个)
电流是电荷的定向移动形成的,所以这些电荷是移动的,不会形成静止的电场,电流具有磁效应,所以会形成磁场,电场和磁场在空间的波动,就像打水漂一样,形成电磁波,所以电流的速度其实就是电磁波的速度,3*10^8m/s.电磁波产生的原因可以简单概括为
随时间 变化的电流 产生 随时间 变化的磁场
而 这个变化的磁场又产生了变化的电场 接着电场又产生磁场。。。。
反复循环 一直到能量消耗尽为止 就形成了电磁波的传播
所以当 电流变化时 产生了 电磁波所以有电场和磁场变化就有 电磁波的存在 所为”波“是一种能量的传播
而电场和磁场 是一种 非接触场 不需要 介质也能传播
但是在不同的介质 形成的场的强度不同(因有能量损耗)
即使在太空里所为”真空“ 也不是 绝对的不含任何物质的空间
会有宇宙射线 宇宙尘埃等 也就是说真实世界
不存在 绝对真空——不包含一切物质的空间 (黑洞不知道)
所以在介质 即使 包括物理书上称为的真空中 电磁波 传播也有能量损耗
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