# Surface Charge

From Soft-Matter

**Surface charge** is the amount of charge located on the surface of an object. It is quantified most usually by the surface charge density, which is charge per unit area. In the case where the charge is uniformly distributed along the surface, the surface charge density is simply

<math>\sigma = \frac{Q}{A}</math> ,

where Q is the total charge, and A is the total area. However, in the more general case, we can define the surface charge density by <math>dq = \sigma da'</math>, where da' is an element of area on the surface and dq is the charge located in that element.

## Reference

[1] D. Griffiths, "Introduction to Electrodynamics," Third Edition, Prentice Hall (2009).