The discussion centers on the phenomenon of phase change in electromagnetic (EM) waves when reflected from a boundary between two media, particularly focusing on why a 180° phase change occurs when reflecting from a denser medium. The scope includes theoretical explanations and conceptual clarifications related to wave behavior at boundaries.
Participants express various viewpoints regarding the mechanisms behind the phase change, with some agreeing on the role of impedance and continuity, while others question the implications of these concepts. The discussion remains unresolved with multiple competing explanations present.
Limitations include varying levels of understanding among participants, dependence on definitions of impedance and phase velocity, and the need for further clarification on the conditions under which phase changes occur.
The 'reason' can be explained in terms of a change of impedance and the requirement for continuity at the boundary. At the interface, there has to be continuity of E and H fields - as a wave crosses, if the ratio of E/H changes (different phase velocity) then there must be a reflected wave because all the energy can't pass through. One or other of the Electric or Magnetic fields in the reflected wave will be in anti phase so that there is no change in field across the boundary. Which one changes sign, depends on whether the impedance of the second is greater or less than the impedance of the first medium.sheld said:Why phase difference of EM wave is changed 180 degrees reflected from denser medium?
I will be glad if u give me the actual reason [emoji4]
The OP wants a reason / explanation, though. Why would you expect the reflection from a lower index of refraction boundary to be in phase?Leesa Johnson said:An electromagnetic wave undergoes a phase change of 180° upon reflection from a medium that has a higher index of refraction than the one in which the wave is traveling.