An electric dipole of moment `p` is kept at a distance `r` form an infinite long charged wire of linear charge density `lambda` as shown.Find the force acting on the dipole?

Explanation

Field intensity at a distance r from the line of charge is `E=(lamda)/(2 pi epsilon_(0)r)`
The force on the dipole is `F=-p(dE)/(dr)`
`=-p[(-)/(2 epsilon_(0)r^(2))]=p/(2 epsilon_(0)r^(2))`
Here the net force on dipole due to the wire will be attractive.