So here is the scenario (see attachment) - I have a semicircle wire (radius R=15.9cm) which is made of insulator material , the semicircle consist of two combined quartercircle wires parts where one has equally distributed charge +Q and the other has -Q . Required is find the Electric field in direction of x at the origin . Q=5.33nC(adsbygoogle = window.adsbygoogle || []).push({});

My approach was as follows

Let E = 1/(4*pi*e)∫1/(R^2).dQ r

dQ=λ*ds and ds=R*dθ and i also know that unit vector r = cosθ*i+sinθ*j

therefore for the E in x direction i get this expression

E = 1/(4*pi*e)*1/(R^2)*λ*R∫cosθ.dθ

Integrating from 0 to pi ( thus taking only half of the semicircle ) and using λ as 2/(pi*r)

I get Q/(2*pi^2*e*R^2) .

Because the other half has opposite charge i can say that the Etot = Eneg +Epos

Therefore i multiply the equation by two to finaly get

Q/(pi^2*e*R^2)

If i put the values given i get as absolute value 2413 N/C for Electric field at origin of circel in the direction of x

Unfortunately it is a wrong solution :( !! What is the mistake i hv done ?? Can anyone spot it ? Thanks in advance

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# Electric Field of extended mass

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