Question

Two charged particles with charge 2.0 × 10⁻⁸ C each are joined by an insulating string of length 1 m and the system is kept on a smooth horizontal table. Find the tension in the string.

Answer 1

Given:
Magnitude of the charges, q =  2.0 × 10⁻⁸ C
Separation between the charges, r = 1 m
The tension in the string will be same as the electrostatic force between the charged particles.
So,  

\[T = F\]

By Coulomb's Law,         

\[F = \frac{1}{4\pi \epsilon_0}\frac{q^2}{r^2}\]

\[\Rightarrow T = \frac{9 \times {10}^9 \times \left( 2 . 0 \times {10}^{- 8} \right)^2}{1^2}\] 

\[                   = 3 . 6 \times  {10}^{- 6}\] N