General physics 2 Electricity & Magnetism: Lecture 1

General physics 2: Electricity & Magnetism products about Electric Charge and Field (Electric Charges; Coulomb’s Law; Electric Fields; Electric Field of a Continuous Charge Distribution; Motion of Charged Particles in a Uniform Electric Field).
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General physics 2 Electricity & Magnetism: Lecture 1 Ngac An Bang, Faculty of Physics, HUS GENERAL PHYSICS 2Electricity & Magnetism 1 Ngac An Bang, Faculty of Physics, HUSPhysics 2 Text book: Fundamentals of Physics, David Halliday et al., 8th Edition. Physics for Scientists and Engineers, Raymond A. Serway and John W. Jewett, 6th Edition. Instructor: Dr. Ngac An Bang Faculty of Physics, Hanoi University of Science ngacanbang@hus.edu.vn Homework: will be assigned and may be collected. Quizzes and Exams: There will be at least two (02) 15-minute quizzes. There will be a mid-term exam and a final exam. Grading policy: Homework and Quizzes: 20 % Midterm exam: 20 % Final exam: 60 % 2 Ngac An Bang, Faculty of Physics, HUS Physics 2 Lecture 1 Electric Charge and Field Electric Charges Coulomb’s Law Electric Fields Electric Field of a Continuous Charge Distribution Motion of Charged Particles in a Uniform Electric Field 3Electric Charge and Field Ngac An Bang, Faculty of Physics, HUS Mother and daughter are both enjoying the effects of electrically charging their bodies. Each individual hair on their heads becomes charged and exerts a repulsive force on the other hairs, resulting in the “stand-up’’ hairdos that you see here. (Courtesy of Resonance Research Corporation) 4 Electric Charge and Field Ngac An Bang, Faculty of Physics, HUS Electric Charge Electric charge Some simple experiments demonstrate the existence of electric forces and charges There are two types of charge. Convention dictates sign of charge: Positive charge Negative charge 5 Like charges repel, and opposite charges attract.Electric Charge and Field Ngac An Bang, Faculty of Physics, HUS Electric ChargeQuantization of Charge Charge is quantised The smallest unit of “free” charge known in nature is the charge of an electron or proton, which has a magnitude of e = 1.602 x 10-19 C Charge of any ordinary matter is quantized in integral multiples of the elementary charge e, Q = ± Ne. An electron carries one unit of negative charge, -e, While a proton carries one unit of positive charge, +e. Note that although quarks (u, d, c, s, t, b) have smaller charge in comparison to electron or proton, they are not free particles. 6Electric Charge and Field Ngac An Bang, Faculty of Physics, HUS Electric ChargeCharge conservation A universal conservation law • In a closed system, the total amount of charge is conserved since charge can neither be created nor destroyed. • A charge can, however, be transferred from one body to another. • The β- reaction n → p + e + νe 0e = 1e -1e + 0e n(udd), p(uud) d → u + e + νe • Electron-positron annihilation e- + e+ → γ + γ • Pair production (γ-conversion) γ → e- + e+ 7Electric Charge and Field Ngac An Bang, Faculty of Physics, HUS Electric ChargeSome basic concepts All materials acquire an electric charge Neutral object: Total positive charge Q+= Total negative charge Q-. Positively charged object: Q+ > Q-, Negatively charged object: Q+ < Q- In this part, we consider only two types of materials • Conductors: Electrical conductors are materials in which some of the electrons are free electrons that are ...