An Electric Charge 1An electric charge is a physical property of electrons and protons in the atoms of matter that gives rise to forces between atoms. The charge is measured in coulomb [C]. The charge of a proton is arbitrarily chosen as positive and has the value of 1:601  1019 C, whereas the charge of an electron is chosen as negative with a value of 1:601  1019 C. Like charges repel while unlike charges attract each other. The electric charges obey the principle of conservation (i.e., charges cannot be created or destroyed).