Does a light pulse get amplified when it goes to a less dense medium?

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Discussion Overview

The discussion centers on whether a light pulse experiences amplification when transitioning from a denser medium to a less dense medium, drawing a comparison to mechanical waves in strings. The scope includes theoretical considerations and conceptual clarifications regarding light propagation and energy transmission in different media.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that a string pulse amplifies when moving to a less dense medium, questioning why light does not exhibit similar behavior.
  • Another participant references an external thread for further reading, implying that additional context may be available.
  • A different viewpoint introduces the idea that the electromagnetic field serves as the medium for light, which may influence its behavior.
  • Another participant argues that light does not transition to a "different medium," suggesting a different interpretation of medium changes.
  • A participant discusses the energy dynamics when light moves from glass to air, noting that while the amplitude of the electric field increases, there is also a 4% reflection loss, leading to a decrease in transmitted energy despite the increase in amplitude.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of light when transitioning between media, with no consensus reached on whether amplification occurs or how to interpret the changes in energy and amplitude.

Contextual Notes

Participants mention specific values related to the index of refraction and energy reflection, but the discussion does not resolve the implications of these values on the overall behavior of light in different media.

quantum123
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Since a string pulse get amplified when it enters a less dense medium such as from the thick heavy rope to a lighter string, why does not light do the same?
 
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Come to think of it, there is a medium and the medium is the electromagnetic field.
 
It never goes to a "different medium".
 
When light goes from a medium such as glass (index of refraction n=1.5) to air, about 4% of the energy is reflected, and 96% of the energy is transmitted. The ratio of the transverse E (electric) vector to the transverse H (magnetic) vector in light is proportional to 1/n, so the ratio E/H increases when the light goes from glass to air. But the transmitted energy decreases by 4%. So the amplitude E increases, but the transmitted energy, which is proportional to E times H (Poynting vector), decreases.
Bob S
 
Thanks, Bob!
 

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