Q.The SI Unit of linear charge density is

When more than two charges are present, the net force (or field) on any one charge is the VECTOR sum of the individual Coulomb contributions from every other charge, each computed as though the rest were absent -- never a simple sum of magnitudes, since the individual contributions generally point in different directions. For a very large number of closely spaced charges (a charged wire, plate or solid body), it is more practical to describe the charge as smeared out continuously using a charge density: linear $\lambda=dq/dl$ (C/m) for a wire, surface $\sigma=dq/dA$ (C/m$^2$) for a shee …