Question

Two small balls having equal positive charges $Q$ (coulomb) on each are suspended by two insulating strings of equal length $L$ (metre) from a hook fixed to a stand. The whole setup is taken in a satellite into space where there is no gravity (state of weightlessness). The angle between the strings is.......and the tension in each string is........newton

Answer 1

Due to electrostatic repulsion the charges will move as farthest as possible and the angle between the two strings will be $180^{\circ }$ as shown in figure.
Tension in each string will be equal to the electrostatic repulsion between the two charges.
Thus,
$T=F_e=\frac{1}{4\pi {\epsilon }_0}\cdot \frac{Q\times Q}{(2L{)}^2}=\frac{Q^2}{16\pi {\epsilon }_0{L}^2}$