According to electromagnetism, charge density is defined as a measure of electric charge per unit volume of the space in one, two or three dimensions. To be specific, the linear surface or volume charge density is the amount of electric charge per surface area or volume, respectively.
Surface charge describes the electric potential difference between the inner and outer surface of different states like solid and liquid, liquid and gas or gas and liquid. The surface charge density is present only in conducting surfaces and describes the whole amount of charge q per unit area A.
Hence, the Surface charge density formula is given by,
σ=qA
Where,
q = charge and
A = surface area.