A line charge of uniform density [tex]\lambda[/tex] forms a semi-circle of radius R0. Determine the magnitude and direction of the electric field intensity at the center of the semi-circle. I won't bother with uploading a picture I'm pretty sure you can picture this without. My trouble with this is I'm unsure whether I need to do a double integral. So here is my working. E = (1/4[tex]\pi[/tex][tex]\epsilon[/tex]) q/r2 r As the problem is symmetric only the cos([tex]\theta[/tex]) components add. So for a small piece of charge dq Ei = (1/4[tex]\pi[/tex][tex]\epsilon[/tex]) dq/R02 cos([tex]\theta[/tex]) Now for this I have to sum up all the dq's but they are also all have a different angle. So do I do an integral for theta from -[tex]\pi[/tex]/2 to [tex]\pi[/tex]/2 ? Anyway the answer I get is [tex]\lambda[/tex]/2[tex]\epsilon[/tex]R0 Any help with this would be greatly appreciated. P.S. I'm new to latex.