(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

find electric flux that enters left hand side of a cone (with base radius R and height h). electric field penetrates the cone horizontally (cone is on a horizontal table).

2. Relevant equations

flux = surface integral of EdA

where E represents component of electric field normal to surface

3. The attempt at a solution

so that's the formula I got from my book... so I thought I had to find the integral of Ecos(theta)dA.... since Ecos(theta) would be the component of E that's normal to slanted surface of the cone... and if I integrate with respect to A I get Ecos(theta)A... cos(theta) is h/sqrt(h^2+R^2).... area of cone (minus the base) is pi*R*sqrt(h^2+R^2)...

so I did... E*(h/sqrt(h^2+R^2))*[pi*R*sqrt(h^2+R^2)]/2

once I cancel out stuff, I get: E*(h)(pi*R)/2... 2piERh

however, the back of my book says the answer is ERh... why??

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# Flux through surface of half a cone

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