A point charge `q_(A)=+100 mu c` is placed at point A (1, 0, 2) m and another point charge `q_(B)=+200 mu c` is placed at point B (4, 4, 2) m. Find :
(i) Magnitude of electrostatic interaction force acting between them
(ii) Find `vec(F)_(A)` (force on A due to B) and `vec(F)_(B)` (force on due to A) in vector form

Explanation

Force on B `vec(F)_(B) = (kq_(A)q_(B))/(|vec(r )|^(3)) vec(r )`
`= ((9 xx 10^(9))(100 xx 10^(-6))(200 xx 10^(-6)))/(sqrt((4-1)^(2)+(4-0)^(2)+(2-2)^(2)))[(4-1)hat(i) + (4-0) hat(j) + (2-2)hat(k)]`
`= 7.2 ((3)/(5)hat(i) + (4)/(5)hat(j))N`
Similarly `vec(F)_(A) = 7.2 (-(3)/(5)hat(i) - (4)/(5)hat(j))N`
Concept -
Action `(vec(F)_(A))` and Reaction `(vec(F)_(B))` are equal but in opposite direction.