How exactly does a mood ring work?

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Discussion Overview

The discussion revolves around the functioning of mood rings, specifically focusing on the mechanisms behind their color changes in response to temperature. Participants explore the underlying principles of liquid crystal structures and light absorption, as well as personal experiences with mood rings.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant explains that the liquid crystal structure in mood rings expands and contracts with temperature changes, affecting which wavelengths of light are reflected due to constructive interference.
  • Another participant states that wavelengths not matching the specific conditions are either absorbed or transmitted, though this response is met with skepticism regarding its clarity.
  • A participant shares a personal anecdote about an old mood ring, noting that without functional liquid crystal material, the ring absorbs all incident light, suggesting a black backing material contributes to this absorption.
  • There is a suggestion that mood rings contain thermochromic elements that change color in response to body temperature.

Areas of Agreement / Disagreement

Participants express differing levels of understanding regarding the absorption of light and the mechanisms of mood rings. There is no consensus on the clarity of the explanations provided, and some participants seek deeper insights into the topic.

Contextual Notes

Some participants indicate a lack of clarity in the explanations about absorption and the functioning of mood rings, suggesting that further details or resources may be necessary for a comprehensive understanding.

Who May Find This Useful

This discussion may be of interest to individuals curious about the science behind mood rings, particularly those looking for technical explanations of liquid crystal behavior and light absorption.

Edi
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Ok, I understand that the liquid crystal structure expands and contracts in response to thermal fluctuations and that the structure is made of layers... and only the wavelengths that mach exactly or are half (or quarter and so on) can have constructive interference, thus, only those wavelengths are supposed to be reflected from the ring/ crystal structure... BUT - what happens to all the other wavelengths, that do not mach those certain lengths at specific temperature? .. yes, they do not act in constructive interference, but .. where do they go/ why are they absorbed?
 
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They are absorbed or transmitted.
 
Well. that explains pretty much nothing.
.. where can I gen a deeper insight on this? .. knowing exactly how..
 
I dug out my original '70's mood ring from a box in my desk, where it sat under my Elvis concert ticket stub - either my mood has grown very dark with age, or the ring no longer works. :smile: But it was instructive, with no heat and/or non-functioning liquid crystal material (not sure why it no longer functions), the ring is dark, meaning all the incident light is absorbed - probably by a backing material that is black, which means that the incident light is transmitted through the faux-stone and through the crystal layer. If the liquid forms a periodic array as it should, then some light wavelengths will reflect while the rest transmit to the black layer and are absorbed. The periodicity changes with temperature, so the apparent reflected color changes with temperature.
 
Edi said:
Well. that explains pretty much nothing.
.. where can I gen a deeper insight on this? .. knowing exactly how..

What part of absorption don't you understand? We can help you better if you be more specific. If you just want a general introduction to absorption, it would be more productive to read the http://en.wikipedia.org/wiki/Absorption_%28electromagnetic_radiation%29" article than for me to retype it here.
 
Last edited by a moderator:
Mood Rings contain thermochromic elements. Mood ring color changes in response to the body temperature.
 

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