A total charge \(Q\) is broken in two parts \(Q_1\) and \(Q_2\) and they are placed at a distance \(R\) from each other. The maximum force of repulsion between them will occur, when:

Two charges \(+2\) C and \(+6\) C are repelling each other with a force of \(12\) N. If each charge is given \(-2\) C of charge, then the value of the force will be:

Two positive ions, each carrying a charge \(q\), are separated by a distance \(d\). If \(F\) is the force of repulsion between the ions, the number of electrons missing from each ion will be:
(\(e\) is the charge on an electron)

The acceleration of an electron due to the mutual attraction between the electron and a proton when they are \(1.6~\mathring{A}\) apart is:
\(\left(\dfrac{1}{4 \pi \varepsilon_0}=9 \times 10^9~ \text{Nm}^2 \text{C}^{-2}\right)\)

Two small spheres each having the charge \(+Q\) are suspended by insulating threads of length \(L\) from a hook. If this arrangement is taken in space where there is no gravitational effect, then the angle between the two suspensions and the tension in each will be:

1. ${180}^o,$ $\frac{1}{4\pi {\epsilon }_0}\frac{Q^2}{{\left(2L\right)}^2}$

2. ${90}^o,$ $\frac{1}{4\pi {\epsilon }_0}\frac{Q^2}{L^2}$

3. ${180}^o,$ $\frac{1}{4\pi {\epsilon }_0}\frac{Q^2}{2L^2}$

4. ${180}^o,$ $\frac{1}{4\pi {\epsilon }_0}\frac{Q^2}{L^2}$ 

Four charges are arranged at the corners of a square \(ABCD\) as shown in the figure. The force on a positive charge kept at the center of the square is: