Electrostatics: Electric Charge, Electrification, Electric Field, and Electrostatic Force, Lecture notes of Physics

Download Electrostatics: Electric Charge, Electrification, Electric Field, and Electrostatic Force and more Lecture notes Physics in PDF only on Docsity! 1 Electricity (Part I) Electrostatics In this lecture Electricity Electric Charge Electrification Electrostatic Charge Electric Field Electrostatic Force Lines of Equipotential Electricity • X-ray tube converts electric energy into electromagnetic energy • Other devices convert electric energy into other forms of energy – Kinetic energy: – Heat energy: – Chemical energy: Matter • Matter has mass, form and energy equivalence. • Matter may also have electric charge Electric Charge • Comes in discrete quanta – Negative or positive – Electrons & Protons – Equal in magnitude, opposite in sign • In most cases the net charge of matter is neutral – Total negative charge balances total positive charge Electric Charge • Electrons are often free to move form the outer shell of one atom to another • Protons are fixed in the nucleus and are not free to move 2 Electrification • Material takes on net charge (+ve or –ve) • Outer-shell electrons of some types of atoms are loosely bound and can easily be removed • Removal of these electrons leaves the material with a net positive charge • Created by contact, friction or induction Electrification • Electrification causes static (stationary) charge • Electrostatics is the study of stationary electric charge Electrification • Electrification occurs due to movement of negative charge • Positive charge remains in material • Transfer of electrons from one object to another causes the first object to become positively and the second to become negatively charged Electrostatic Charge • Smallest unit of charge (electron) far too small to be useful • Units of electric charge: Coulombs (C) – Charles Coulomb (1736-1806) – 1 Coulomb = 6.24 X 1018 electron charges – Electron charge = 1.6 X 10-16 C Electrostatic Charge Example: An electrostatic charge is transferred between two people after one has scuffed their feet across a nylon rug is of the order of one microcoulomb. How many electrons are transferred? •Unlike charges attract •Like Charges repel