Question

Two infinite linear charges are placed parallel to each other at a distance $0.1m$ from each other. If the linear charge density on each is $5\mu C/m$, then the force (in $N/m$ ) acting on a unit length of each linear charge will be

Answer 1

Answer: 4.50

Electric field at $2$ due to $1$,

$E=\frac{5\times 10^{-6}}{2\pi {\epsilon }_0(0.1)}$
Force per unit length on wire$2$ ,
$F=E\times$ Charge on unit length of wire $2=E\times 5\times 10^{-6}$
$=\frac{5\times 10^{-6}\times 5\times 10^{-6}}{2\pi {\epsilon }_0\times (0.1)}=4.5N/m$