Electric Charge
Part of the Electricity and Magnetism section of Coddy's Physics journey. Lesson 1 of 51.
Electric charge comes in two kinds, positive and negative. Like charges repel, opposite charges attract.
Charge is measured in coulombs (C).
A proton carries +e and an electron −e, with e = 1.6 × 10⁻¹⁹ C. A neutral object has as many electrons as protons. Extra electrons make it negative, missing ones positive:
q = n e
Charge is never made or destroyed, only moved. Electrons move freely in a conductor (a metal) and stay put in an insulator (plastic, glass). Two identical metal spheres that touch share their total charge equally.
Challenge
A metal sphere starts neutral. Rubbing takes 5 × 10¹² electrons off it. What charge q does the sphere have now, in microcoulombs?
Try it yourself
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
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