In Fig. a, particle 1 (of charge `q_(1)`) and particle 2 (of charge `q_(2)`) are fixed in place on an x axis, `8.00` cm apart.

Particle 3 (of charge `q_(3)=+8.00xx10^(-19)C`) is to be placed on the line between particles 1 and 2 so that they produce a net electrostatic force `F_("net")=2F_(0)` on it Figure b gives the x component of that force versus the coordinate x at which particle 3 is placed. The scale of the x-axis is set by `x_(s)=8.0`cm. What are (a) the sign of charge `q_(1)` and (b) the ratio `q_(2)//q_(1)`?

Answer

(a) Positive (b) 9