Non uniform surface charge density

jeudi 31 juillet 2014

hello.

The problem is : A metallic horizontal disk of radius R has been charged on its top surface with a total charge Q such that its surface charge density is "non uniform" and governed by the expression σ=q|cosθ|*r where r and θ are the polar coordinates measured from the center O of the disk.

Determine in terms of Q and R the value of q.

I tried to solve it using double integral but it didn't work.

σ=dq/ds then dq=q|cosθ|*r*rdrdθ then ∫dq/q=0R 02∏|cosθ|dθr2dr.

If any body can help thanks.





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