3brother ur qn is not clear.
4 Answers
1the ques. is
a thin glass rod is bent into a semicircle of radius R. a charge +q is uniformly distributed along d upper half nd a charge -q is uniformly distributed along d lower half as shown in d above figure. find d electric field at d centre of semi-circle
ans= q /( (pi)^2 \epsilon R^2 )
62First find teh electric field due to a quarter circle....
Then proceed..