# Two charged particles having charge $\;2.0\times10^{-8}\;C\;$ each are joined by an insulating string of length 1m and the system is kept on smooth horizontal table . Find the tension in the string

$(a)\;36\times10^{-6}\;N\qquad(b)\;0.36\times10^{-6}\;N\qquad(c)\;3.6\times10^{-6}\;N\qquad(d)\;None\;of\;these$

Answer : (c) $\;3.6\times10^{-6}\;N$
Explanation :
$T=\large\frac{k\;q^2}{r^2}$
$T=\large\frac{9\times10^9\times4\times10^{-16}}{1}$
$T=3.6\times10^{-6}\;N\;.$