Quick questions on Electric charge and Coulomb's law - TCE Physics (Tasmania)

Charge is a fundamental property of matter, carried by protons (positive) and electrons (negative). Charge is quantised in units of the elementary charge $e = 1.6 \times 10^{-19}\ \text{C}$, and it is conserved, meaning it can be transferred but never created or destroyed. An object becomes negatively charged by gaining electrons and positively charged by losing them; the protons in the nucleus do not move.

Objects can be charged in three ways:

When more than two charges are present, the net force on one charge is the vector sum of the individual Coulomb forces from every other charge (the principle of superposition). Calculate each pairwise force separately with magnitudes, draw its direction (toward an attracting charge, away from a repelling one), then add the forces as vectors, resolving into $x$ and $y$ components when they are not along a single line. For charges at the corners of a triangle, symmetry often makes one component cancel, which saves work.