Asperities are nano-scale bumps of an object and where contact actually happens. This image shows two jagged asperities under contact with each other. The upper half is grey and positively charged, while the bottom half is a much darker grey and negatively charged. Appropriate charge signs (+ and -) can be seen near the places where the two asperities contact.
This file was derived from: Asperities.svgUpper half with charge signs added
Aaron Liu, TotoBaggins, Mckdandy