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the7piano
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Homework Statement
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.
Homework Equations
dE = (k dq)/r^2
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 !
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