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Physics · Glossary

What is Charging by friction and by contact?

Also known as: charging by friction · charging by contact

Definition 13.8 High School Physics · Chapter 13 — The Fundamental Interactions

Rubbing two insulators tears electrons off one and onto the other, leaving opposite charges of equal magnitude (charging by friction); touching a charged object to a neutral one shares the charge (charging by contact). Only electrons move; the total charge is conserved.

Examples

Example 13.9 (Counting electrons)

A balloon rubbed on hair acquires q=−1.6×10−8 Cq = -1.6 \times 10^{-8}\,\mathrm{C}: it has gained N=1.6×10−8/1.6×10−19=1.0×1011N = 1.6 \times 10^{-8} / 1.6 \times 10^{-19} = 1.0 \times 10^{11} electrons, and the hair is left with exactly +1.6×10−8 C+1.6 \times 10^{-8}\,\mathrm{C}.

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