A point charge q is placed at a distance r from a very long charged thread of unoform linear charge density `lambda`. Find out total electric force experienced by the line charge due to the point charge. (Neglect gravity).

Explanation

Force on charge q due to the thread, `F=((2K lambda)/r).q` By Newton's III law, every action has equal and opposite reaction, so force on the thread `= (2 K lambda)/r. q`
(away from point charge)