Two coaxial rings, each of radius R, made of thin wire are separated by a small distance `l(l lt lt R)` and carry the charges `q` and `-q`. Find the electric field potential and strength at the axis of the system as a function of the x coordinate (see figure). Investigate these functions at `|x| gt gt R`

Answer

`phi=(ql)/(4piepsi_(0))(x)/((R^(2)+x^(2))^(3//2))=E_(x)=(ql)/(4piepsi_(0))(R^(2)-2x^(2))/((R^(2)+x^(2))^(5//2))` where `E_(x)` is the projection of the vector `vecE` on the x-axis The fnctions are plottted in figure If |x|gtgtR, then `omega~~(ql)/(4piepsi_(0)x^(2))andE_(x)~~(ql)/(2piepsi_(0)x^(3))`
`(##GAL_PHY_V03A_ECA_C01_E01_232_O01##)`