Confused about this force calulation in Resnick Halliday Krane Electrostatics

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SUMMARY

The discussion centers on a misunderstanding regarding the calculation of electrostatic force in the Resnick Halliday Krane textbook, specifically in Sample Problem 25-7. Participants agree that the book incorrectly states that the Coulombic force decreases by a factor of 1/8 without properly accounting for the reduction in distance, which also affects the force calculation. The correct interpretation should consider both the charge ratio and the distance ratio, leading to a different conclusion about the force. This clarification is crucial for students beginning their studies in electromagnetism.

PREREQUISITES
  • Understanding of Coulomb's Law
  • Familiarity with electrostatic force calculations
  • Basic knowledge of charge interactions
  • Concept of distance in electrostatic contexts
NEXT STEPS
  • Review Coulomb's Law and its applications in electrostatics
  • Study the concept of electric field strength and its relation to force
  • Learn about the implications of distance changes on electrostatic forces
  • Examine additional problems in Resnick Halliday Krane for further practice
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Students of electromagnetism, physics educators, and anyone seeking to clarify concepts related to electrostatic forces and their calculations.

KnightTheConqueror
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TL;DR
Resnick Halliday Krane Electrostatics Sample Problem 25-7 doubt
I'm confused in the calculation for R/2. The author took in account that the charge will change by a factor 1/8. But how does it show that the coloumbic force will become 1/8th. The distance will also reduce by half shouldn't that also be taken into account? Or am I missing something here?
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KnightTheConqueror said:
TL;DR Summary: Resnick Halliday Krane Electrostatics Sample Problem 25-7 doubt

I'm confused in the calculation for R/2. The author took in account that the charge will change by a factor 1/8. But how does it show that the coloumbic force will become 1/8th. The distance will also reduce by half shouldn't that also be taken into account? Or am I missing something here?View attachment 336703
Been there, done that. You are correct and the book is wrong. See discussion here.
https://www.physicsforums.com/threa...rted-on-an-electron-inside-a-nucleus.1052346/
 
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I agree with you - they've correctly calculated the charge ratio and forgotten the distance ratio.

Edit: beaten to it, I see.
 
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:welcome:
 
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KnightTheConqueror said:
Thank you, i just started electromagnetism and i got disappointed that perhaps I'm not getting proper grasp of the concepts. Thanks for clarifying the book is wrong
I wish you success with your studies. If you need more help, you know where to find it.
 

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