Reflection of light - the physics of a mirror

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Discussion Overview

The discussion revolves around the physics of light reflection, particularly in relation to mirrors and their behavior at both macroscopic and sub-atomic levels. Participants explore the mechanisms behind reflection, the comparative effectiveness of different materials, and the underlying principles of wave behavior in optics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions how light reflection occurs at a sub-atomic level, proposing two possibilities: excitation of electrons or particle collisions.
  • Another participant asserts that reflection is a wave behavior phenomenon that requires a smooth interface at the wavelength scale, suggesting that sub-atomic interactions are not the primary mechanism.
  • A participant inquires about the reasons why silver reflects light more effectively than wood.
  • Another participant explains that the smoothness of the surface and the electrical properties of materials contribute to their reflective capabilities, noting that silver's superior conductivity allows for better reflection compared to wood.
  • It is mentioned that the principles of wave behavior apply generally, not just to light waves, and similar behaviors are observed in acoustics.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms of light reflection, particularly at the sub-atomic level, with no consensus reached on the exact processes involved. There is agreement on the factors affecting reflection quality between different materials, but the foundational understanding of reflection remains contested.

Contextual Notes

The discussion highlights the complexity of wave behavior and its dependence on material properties, but does not resolve the assumptions regarding sub-atomic interactions or the specific definitions of reflection mechanisms.

Tachyonie
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How does reflecting of a light works? In physics people keep talking about mirrors in lasers and optics, etc. but how does mirror works at sub-atomic level? Does the light wave simply excite the electron which then sends identical wave in opposite direction? Or does it simply bumps off a particle? Can mirror be heated by a laser?
 
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Tachyonie said:
How does reflecting of a light works? In physics people keep talking about mirrors in lasers and optics, etc. but how does mirror works at sub-atomic level? Does the light wave simply excite the electron which then sends identical wave in opposite direction? Or does it simply bumps off a particle? Can mirror be heated by a laser?
A mirror doesn't work at a sub-atomic level. Reflection is a type of wave behavior, and it only occurs when you have an interface that is smooth at the scale of a wavelength.
 
So why does silver object reflect the light more clearly than a wood for example.
 
Tachyonie said:
So why does silver object reflect the light more clearly than a wood for example.
There are two factors here.

First, the smoothness of the surface at the level of a wavelength, a silver object is smoother than a wood object. It would be very difficult to smooth the wood to the same level without adding some sort of polishing agent, but if you made the silver rough like the wood it would not reflect as well as a smooth mirror. But it would still reflect better than the wood. (The same thing happens acoustically, a smooth rock wall makes a better echo than a jumble of rocks.)

Second, the electrical properties. Silver is a much better conductor than wood. This means that E-fields can go much deeper in wood than in silver. In this sense (the ability to conduct and support E-fields) wood is much more like air than silver. Whenever two media are similar in terms of their wave properties you get less reflection and more absorption or transmission. (The same thing happens acoustically, a rock wall makes a better echo than a soft padded wall.)

These are general features of wave behavior, and not specifically limited to light waves.
 

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