Find Refractive Index of Liquid for Observer with Velocity

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Discussion Overview

The discussion revolves around finding the refractive index of a liquid for an observer moving with a certain velocity relative to the liquid. Participants explore the implications of velocity on refractive index calculations, addressing both theoretical understanding and practical application in a homework context.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a solution to the problem but is challenged on the correctness of their formula for calculating the velocity component.
  • Another participant points out a specific error in the formula used, suggesting that the term should be adjusted to reflect the correct relationship between velocity components.
  • There is a request for further clarification and a complete solution due to an upcoming exam, indicating urgency and a lack of understanding.
  • Responses emphasize the importance of checking work and understanding the derivation process rather than simply providing answers.
  • Dimensional analysis is mentioned as a method to verify the correctness of the final result, highlighting a potential issue with the dimensions of the quantities involved.
  • Participants express embarrassment over mistakes and acknowledge the need for self-checking in their calculations.
  • Despite some corrections being pointed out, one participant insists they have checked their work and found no errors, leading to mixed responses about the correctness of their solution.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the original solution, with some asserting errors while others believe the revised solution is acceptable. The discussion remains unresolved regarding the final accuracy of the calculations presented.

Contextual Notes

Limitations include potential misunderstandings of the velocity composition formula and the implications of dimensional analysis on the results. The discussion reflects a mix of confidence and uncertainty among participants regarding their mathematical reasoning.

Paul Black
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hello

i have this question
" a liquid has refractive index (n). find the refractive index of this liquid for an observer if the liquid have a velocity (v) to this observer "

i have my solution in an attachment
please look at it and tell me if it is the right solution

thank you very much
 

Attachments

  • CCI05282014_00000.jpg
    CCI05282014_00000.jpg
    7.5 KB · Views: 482
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Paul Black said:
hello

i have this question
" a liquid has refractive index (n). find the refractive index of this liquid for an observer if the liquid have a velocity (v) to this observer "

i have my solution in an attachment
please look at it and tell me if it is the right solution

thank you very much

The approach is correct up to the point where you make a mistake in the calculation of [itex]v'_x[/itex]. The formula that you use is incorrect, look at the term [itex]1-\frac{v^2}{c^2} v_x[/itex], what you want is [itex]1-\frac{vv_x}{c^2}[/itex]
 
Last edited:
sorry but i don't get it.
can you explain it more. i thought my formula is correct
or is there something is forget?
what about the rest of the solution

please if you have time, can you give me the complete solution to this question
i have tomorrow an exam and i have no time
please do me this favor
thank you very much
 
Paul Black said:
sorry but i don't get it.
can you explain it more. i thought my formula is correct

No, it isn't.

what about the rest of the solution

Once you make this error, everything else becomes incorrect. You need to learn how to check your own work, especially after your errors are pointed out to you.

please if you have time, can you give me the complete solution to this question
i have tomorrow an exam and i have no time
please do me this favor
thank you very much

We do not do your homework for you, you don't learn anything if I do it for you. I gave you the exact error in your derivation, your speed composition formula is wrong and I pointed out your exact error.
 
To add to what xox has already said. Your end result cannot be correct on dimensional grounds. Dimensional analysis is always a good check to see if your result makes sense. In your case you are subtracting a velocity squared from a velocity in the numerator. Since velocity has dimension length/time, velocity^2 has dimension length^2/time^2 and you cannot add or subtract quantities of different dimensions.
 
omg that is so embarrassing
sorry but I am out of time. that's is the reason for my stupid mistake
i get it and have again my solution in an attachment


We do not do your homework for you, you don't learn anything if I do it for you. I gave you the exact error in your derivation, your speed composition formula is wrong and I pointed out your exact error.

yes you are soooo right.

thank you again
 

Attachments

  • CCI05282014_00001.jpg
    CCI05282014_00001.jpg
    9.2 KB · Views: 481
Paul Black said:
omg that is so embarrassing
sorry but I am out of time. that's is the reason for my stupid mistake
i get it and have again my solution in an attachment




yes you are soooo right.

thank you again

It is better but you still have algebraic errors. Check your work.
 
i checked it but didnt find any errors
 
Paul Black said:
i checked it but didnt find any errors

Yes, it is right now.
 
  • #10
Ok. Thank you for your help
 

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