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A question on electric fields

  • Thread starter j-lee00
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95
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What is the field near a square metal plate (with infinitesimal thickness)

The answer is E = [tex]\sigma[/tex] / [tex]\epsilon[/tex]

where [tex]\sigma[/tex] = Charge per unit area

[tex]\epsilon[/tex] = relative permeabily

Please help me to derive this result. using coulombs and then gauss' law
 

Answers and Replies

631
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What will be the first step?
 
95
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For coulomb

[tex]\int[/tex] dE = k [tex]\sigma[/tex][tex]\int[/tex] 1/r^2 dA

Im getting

E = [tex]\sigma[/tex] [tex]\pi[/tex] / 8 [tex]\epsilon[/tex]

The symbolys are multiplying not tothe power of. This result is wrong
 
631
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I didn't understand how did u get that answer.
newayz, try using gauss theorem... what is the Gaussian surface here?
 
95
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no i want to use colomb
 
631
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K, then you have take a disc with infinitesimal width, find electric field due to it, and integrate for radius = 0 to infinity(coz the sheet is infinite)
 
95
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i know
 
95
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im just not getting the right ans
 
631
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k, tell me what is electric field at a distance x from the infinitesimally wide disc of radius r ?
 

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