Figure $\left(a\right)$ shows an arrangement of three charged particles separated by distance $d$. Particles $A$ and $C$ are fixed on the $x$-axis, but particle $B$ can be moved along a circle centred on particle $A$. During the movement, a radial line between $A$ and $B$ makes an angle $\text{θ}$ relative to the positive direction of the $x$-axis (figure $\left(b\right)$) . The curves in figure $\left(c\right)$ give, for two situations, the magnitude $F_{\mathit{\text{net}}}$ of the net electrostatic force on particle $A$ due to the other particles. That net force is given as a function of angle $\text{θ}$ and as a multiple of a basic amount $F_0.$ For example, on curve$1$, at $\text{θ}=180°$ we see that $F_{net}=2F_0$.  For the situation corresponding to curve $1$, what is the ratio of the charge of particle $C$ to that of particle $B$ (including sign)?

Figure $\left(a\right)$ shows an arrangement of three charged particles separated by distance $d$. Particles $A$ and $C$ are fixed on the x-axis, but particle $B$ can be moved along a circle centred on particle $A$. During the movement, a radial line between $A$ and $B$ makes an angle $\text{θ}$ relative to the positive direction of the $x$ -axis (figure $\left(b\right)$). The curves in figure $\left(c\right)$ give, for two situations, the magnitude $F_{\text{net }}$ of the net electrostatic force on particle $A$ due to the other particles. That net force is given as a function of angle $\text{θ}$ and as a multiple of a basic amount $F_0$. For example, on curve$1$, at $\text{θ}=180°$, we see that $F_{\mathrm{net}}=2F_0$.  For the situation corresponding to curve $2$ (dash line) what is the ratio of the charge of particle $C$ to that of particle $B$?

Two small balls having equal positive charge $Q$ (coulomb) on each is suspended by two insulated string of equal length $L$ meter, from a hook fixed to a stand. The whole set-up is taken in a satellite into space where there is no gravity (state of weightlessness). Then the angle between the string and tension in the string is