How'd this happen in my experiment?

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In summary, the angle of refraction for liquid weight density was erratic and depended on the angle of incidence.
  • #1
!Live_4Ever!
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How'd this happen in my experiment??!

Im at a total loss now. As some of u guys may know, I've been doing a science fair project on light refraction. I did the experiment, and somehting most peculiar happened.

It is by Density Order




Liquid Weight Density Angle of Refraction
(1) 170g 1.06 g/mL 29.5°
(2) 164g 1.03 g/mL 31°
(3) 160g 0.99 g/mL 32°
(4) 150g 0.89 g/mL 28.5°
(5) 139.5g 0.785 g/mL 30°

Why the heck is the Angle of refraction so erratic? shouldn't it decrease gradually as density decreases??

I did this experiment dozens and dozens of times (literally, I swear)

How did this happen? Is there some variable I missed due to me being a grade 9 student with limited knowledge and cranial capacities? :approve:
 
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  • #2
Is your idea that the angle of refraction should decrease as density increse based on some equation or law? or is it simply dicted by your everyday life intuition?

I found on the internet* that the density [itex]\rho[/itex] of a liquid and its refractive index [itex]n[/itex] are related through the equation

[tex]\frac{n^2-1}{n^2+2}=\frac{4\pi}{3}\rho \alpha[/tex]

Where [itex]\alpha[/itex] is something called the molecular polarizability. I have no idea what that means either, but it probably means that to each media is associated a different value of [itex]\alpha[/itex], so that the angle of refraction does not depend only on the density, making your results you obtained experimentally more plausible.

I hope that helped somehow.


*http://students.creol.ucf.edu/JunLi/JunLiDocuments/Opt%20Exp%2012,%202002.pdf
 
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  • #3
Now that is hard stuff, well, it was actually based on everyday intuition, I mean, wouldn't anyone think at first that higher density would result in a lower angle of refraction?

Thanks a bunch:) I am sure that Ill put it into good use :biggrin:
 
  • #4
I'm not sure what you mean by correlating the angle of refraction (unless of course you have some specific angles of incidence) ? Wouldn't it make sense to calculate the refractive index, n instead ?

Anyway, your intuition that the refractive index should be a function of density alone is wrong. Refraction is not a macroscopic mechanical phenomenon. It is a microscopic electromagnetic phenomenon. So it will depend on charge distributions in the media.

If we could do physics based on intuition, there would be no need for research. Unfortunately, things don't work that way.
 
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  • #5
Well, I made the Angle of Incidence to 45 degrees, and I did calculate the refractive index on another chart, that was like a rudementary one.

I have been researching for the reason why Density does not affect the Angle of refraction, are there any good sites out there that can help me out? :cry:
 
  • #6
Guys please help me out.. :cry: Its due the day after tomorrow and if I don't understand htis Molecular Polarizability by then I am friend! :cry:
 
  • #7
What is the aim of your experiment ? And what is it you want help with ?

It wouldn't be right to say that the refractive index does not depend on density. It does. But it also depends on other things...and that's what throws the table out of whack.
 
  • #8
Yeah those "other things" are the ones I need to know + understand and that is what I have been tring to find out ever since I conducted my experiment, which is about 2 weeks ago, extremely startling... and to think that it is due tomorrow.. *gasp* :cry:
 

Related to How'd this happen in my experiment?

1. What could have caused this unexpected result in my experiment?

There could be several reasons for an unexpected result in your experiment. It could be due to experimental error, equipment malfunction, or a flaw in your experimental design. It is important to carefully analyze your data and consider all possible factors before drawing conclusions.

2. How can I prevent this from happening again in future experiments?

To prevent unexpected results in future experiments, it is important to thoroughly plan and design your experiment. This includes identifying potential sources of error and taking steps to minimize them. Additionally, carefully following the experimental procedure and accurately recording data can help prevent unexpected results.

3. Could this result be due to a mistake on my part?

It is possible that an unexpected result in your experiment could be due to a mistake on your part. It is important to carefully review your experimental procedures and data to identify any errors that may have occurred. Additionally, having a colleague or mentor review your work can help catch any mistakes that you may have missed.

4. How can I troubleshoot this issue in my experiment?

To troubleshoot an issue in your experiment, first carefully review your experimental design and procedures. Look for any potential sources of error or inconsistencies in your data. If you are still unable to identify the issue, seek guidance from a mentor or colleague who has experience in this area. They may be able to offer insights or suggest alternative approaches.

5. Can this unexpected result be explained by a new discovery or phenomenon?

Occasionally, an unexpected result in an experiment may lead to a new discovery or phenomenon. In these cases, it is important to thoroughly analyze the data and conduct further experiments to confirm and understand the new finding. It is also important to consult with other experts in the field to validate the discovery and its significance.

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