Electric lines of force
No of lines of force per unit area normal to the surface.If there are N lines of force per unit charge then there are Nq lines of force.If we close this charge with a sphereical surface of radius R the the tptal no of lines crossing the surface are qN,Lines of force per unit area in normal direction is
Nq/4 pi r^2 but this the field q/R^2.Both are equal so
Nq/4pi.R^2=q/R^2 ==> N=4pi.
But in the rational system the field=q/4pi.R^2.In this system N=1 i.e one line of force pre unit charge.