How Is Electric Potential Difference Calculated in a TV Tube?

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Homework Help Overview

The discussion revolves around calculating the electric potential difference in a TV tube, where electrons are accelerated towards a screen. The problem involves understanding the relationship between the electric potential difference and the wavelength of the electrons just before they strike the screen.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants explore different methods to calculate the electric potential difference, including using kinetic energy and momentum. Some question the accuracy of the wavelength used in calculations, while others suggest alternative approaches to derive the potential difference.

Discussion Status

There is ongoing exploration of various methods to calculate the electric potential difference, with participants providing different interpretations of the problem. Some participants express confusion over the calculations and the implications of using different values for wavelength. Guidance has been offered regarding the relationship between kinetic energy and potential difference, but no consensus has been reached on the correct approach.

Contextual Notes

Participants note discrepancies in the wavelength values used in the problem statement and calculations. There is also mention of potential grading issues based on the methods employed, with some expressing concerns about fairness in assessment.

  • #31
Physics345 said:
4.4x10^-67/2[(9.11x10^-31)(1.6x10^-17)]
4.4x10^-67/2.92x10-47
=1.5x10^-18
P.D= 1.5x10^-18 x (1/(10x10^-11)^2)
=1.5x10^-18 x (1/1x10-20)
=1.5x10^-18(1x10^20)
=1.5x10^2
=150
that's why i an of the opinion that wavelength must be corrected
 
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  • #32
drvrm said:
thats why i an of the opinion that wavelength must be corrected
What do you mean? by "I an of the opinion must be correct"
 
  • #33
Physics345 said:
What do you mean? by "I an of the opinion must be correct"

I am referring to your teacher's reply which you wrote earlier that the P.D. should be !0^4 order ...that's why i am saying that unless wavelength gets changed to lower value the P.D. can not increase.. if you try only !0^-11 as wavelength you can get that order of P.D.
 
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  • #34
so basically, the wavelength won't allow for any higher P.D. than we are getting here. Basically if I list the work we just did it should explain to him why my answer is correct?
 
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  • #35
This is really silly though, I shouldn't have to explain this to him. He should of done the math him self and came to the conclusion my answer was correct. Praise be to drvrm! I appreciate you helping me teach the teacher. This feels great =) I asked for extra marks for the explanation.
 
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