Why Does Gauss's Law Use Cylinder Circumference Instead of Area?

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SUMMARY

Gauss's Law applies the concept of electric flux to cylindrical surfaces by utilizing the cylinder's circumference rather than its full area. The key takeaway is that the electric field lines do not penetrate the ends of the cylinder, making the relevant area for calculations the lateral surface area, which is determined by multiplying the circumference by the length (L) of the cylinder. This understanding clarifies why the circumference is used in the context of electric flux calculations for cylindrical symmetry.

PREREQUISITES
  • Understanding of Gauss's Law in electrostatics
  • Familiarity with electric field concepts
  • Basic knowledge of cylindrical geometry
  • Ability to perform surface area calculations
NEXT STEPS
  • Study the derivation of Gauss's Law for different geometries
  • Learn about electric field lines and their properties
  • Explore applications of Gauss's Law in various physical scenarios
  • Investigate the implications of cylindrical symmetry in electrostatics
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Students of physics, educators teaching electrostatics, and anyone interested in understanding the applications of Gauss's Law in electric field calculations.

CollegeStudent
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Homework Statement



So I was looking at this site reading up again on Gauss's Law and was a tad confused

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elecyl.html

1st thing on the page...

Homework Equations


The Attempt at a Solution



It states that the electric flux will just be the Electric field times the area of the cylinder...

However in the calculation, the circumference of the cylinder is used...why is that?
 
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CollegeStudent said:
However in the calculation, the circumference of the cylinder is used...why is that?
The circumference times the length L gives the surface area.
 
Oh okay! I was taking into account the full area but since the Electric field lines will never cross through the 2 ends of the cylinder the area needed will just be the circumference times the length..

Thank you Doc Al!
 

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