1. The problem statement, all variables and given/known data A rod of length 2L lies on the x axis, centered at the origen, and carries a line charge density given by t=T(x/L), where T is a constant. (a) Find an expression for the electric field strength at points on the x axis, for x>L (b) Show that for x>>L, your result has the 1/x^3 dependence of a dipole field, and by comparison, determine the dipole moment of the rod. 2. Relevant equations dE = (k dq)/r^2 3. The attempt at a solution dq=Tda, dE= (k dq)/(x-a)^2 = (kT/L) * (a da) / (x-a)^2 integral dE form -L to +L E = (kT/L) * ( - x/(x+L) + x/(x-L) + ln( (x-L)/(x+L)) ) when x>>L , by using binomial expanding, the result what I have 1/x^2 dependence. Help !!!!!!!!