大学物理 ›› 2024, Vol. 43 ›› Issue (10): 39-.doi: 10.16854/j.cnki.1000-0712.240070

• 教学讨论 • 上一篇    下一篇

自由空间中平面电磁波的电场和磁场总是同相位吗?

  

  1. 南京理工大学物理学院,江苏 南京210094
  • 收稿日期:2024-02-08 修回日期:2024-03-05 出版日期:2024-11-15 发布日期:2024-11-29
  • 作者简介:肖传云(1963—),男,湖北省孝感市人,南京理工大学物理学院教授,博导,主要从事大学物理教学和计算材料科学研究工作.

Are the electric and magnetic fields of plane electromagnetic  wave in free space always in phase?

XIAO Chuan-yun,LIU Yu-zhen   

  1. School of Physics,Nanjing University of Science and Technology,Nanjing Jiangsu 210094,China
  • Received:2024-02-08 Revised:2024-03-05 Online:2024-11-15 Published:2024-11-29

摘要: 几乎所有的教材,不论是中文教材还是英文教材,不论是《大学物理》《电磁学》还是《电动力学》,都认为自由空间中平面电磁波的电场与磁场总是同相位的. 本文从麦克斯韦方程组出发,证明上述结论实际上并不总是正确的. 一般情况下,只能说自由空间中平面电磁波的电场与磁场是“同步”的,可以同相位,也可以反相位,取决于坐标系的选择.

关键词: 平面电磁波, 同相位, 同步, 反相位, 自由空间

Abstract: It is stated in nearly all textbooks that the electric and magnetic fields of any plane electromagnetic wave in free space are always in phase,no matter whether the textbooks are in Chinese or in English,whether they are College Physics,Electromagnetics,or Electrodynamics. Based on Maxwell’s equations,we prove in this paper that the above statement is actually not always correct. In general case,we can only state that the electric and magnetic fields of a plane electromagnetic wave in free space are in step,which can be in phase or out of phase,depending on the choice of coordinate systems. 

Key words: plane electromagnetic wave, in phase, in step, out of phase, free space