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Chapter 1 Overview of static electricity( On Electric Force , field and Gauss’ law, Electric potential, capacitance and dielectrics). http://www.fayoum.edu.eg/nmh E-Mail: [email protected] 22-10-2014 FCI 1 اجندة العام الجامعى 2014/2015 •بدء العام الدراسي السبت الموافق .2014/10/11 •اجازة راس السنة الهجرية 25/10/2014 •امتحاااا ااماااف الالااف الدراساال اتوف الساابت 22/11/2014الاال 27/11/2014 . •امتحانات الفصل الدراسي األول من السبت 3/1/2015الى . 22/1/2015 2 FCI 22-10-2014 Hrs / week Course No Marks Course Title Lect Tut Lab Final Y.Work oral Lab Total Exam hours GEN 110 English Language (1) )1( لغة إنجليزية 2 - - 40 10 - - 50 2 GEN 113 Computational Linguistics لغويات حسابية 2 - - 40 10 - - 50 2 GEN 114 Humanities انسانيات 2 - - 40 10 - - 50 2 GEN 120 Mathematics (1) )1( رياضيات 4 3 - 115 20 15 - 150 3 GEN 125 Physics (1) )1( فيزياء 4 3 2 90 25 10 25 150 3 4 - 4 105 15 10 20 150 3 Basics of computer science أساسيات علوم الحاسب CSC160 22-10-2014 FCI 3 Physics 1 Gen 125 : Electricity and Magnetism REF: Physics For Scientists And Engineers 6E By Serway And Jewett Ch. 1 : Overview of static electricity( Ch. 3 - Direct current and circuit on Electric field and Gauss’ law, Electric potential, capacitance and dielectrics). Ch. 2 : Resistance and current: 2-1 Electric Current 2-2 Resistance 2-3 A Model for Electrical Conduction 2-4 Electrical Power 22-10-2014 FCI 3 -1 Electromotive Force 3 -2 Resistors in Series and Parallel 3 -3 Kirchhoff’s Rules 3 -4 RC Circuits 3 -5 Electrical Meters Inductance: Self learning 4 Physics 1 Gen 125 : Electricity and Magnetism Ref: Physics For Scientists And Engineers 6E By Serway And Jewett Ch. 4 : AC circuits: 4.1 AC Sources 4.2 Resistors in an AC Circuit 4.3 Inductors in an AC Circuit 4.4 Capacitors in an AC Circuit 4.5 The RLC Series Circuit 22-10-2014 FCI 4.6 Power in an AC Circuit 4.7 Resonance in a Series RLC Circuit 4.8 The Transformer and Power Transmission 4.9 Rectifiers and Filters 5 The aim of the course • The graduates have to develop a clear understanding of the basic concepts of electricity. • The graduates have to develop a clear understanding of the basic concepts of electronics. • Developing the graduate's skills and creative thought needed to meet new trends in science. • Supplying graduates with basic attacks and strategies for solving problems. 22-10-2014 FCI 6 - Intended Learning Outcomes A- Knowledge and Understanding: B- Intellectual Skills: 1) Concept of electric field, electric flux. 2) Concept dc circuits and Ac circuits. 3) Investigate the characteristics of simple series circuits that contain resistors, inductors, and capacitors and that are driven by a sinusoidal voltage. 4) Strategies for solving problems related to the previous topics. 1) 2) C- Professional and Practical Skills: 1) 2) 3) D- General and transferable Skills 1) 2) 3) 22-10-2014 FCI Utilizations of theories, rules and basic sciences to interpret physical events. Collecting information from its relevant sources and use it in discussion. Being able to solve problem sheets related to the material course. Collect and record data and information from libraries and summarize it in suitable forms. The student would be able to apply some experiments related to the course contents. Graduate should be able to access data and information from the Internet related to the course subjects. Graduate should develop self professional, scientific, and personal attitude towards continuous education. Graduate should be able to cooperate in teams 7 Chapter 1 Electric Charge and Electric Fields What is a field? What causes fields? Field Type gravity electric magnetic 22-10-2014 FCI Caused By mass charge moving charge 8 Electric Charge Types: Two types of charges Positive: Lack of electrons Negative: surplus of electrons Unit : Coulomb + + 22-10-2014 FCI C - 9 Materials Insulators: do not allow charges to move through them(wood , paper…… ) Conductors: allow charges to move through them ( copper…… Semiconductors: partially allow charges to move through them ( Si , Ge ……. 22-10-2014 FCI 10 Charging: 1-Contact 2-Friction(Rubbing) 3-Induction 22-10-2014 FCI 11 Charging: -Contact +++ +++ 2 1 22-10-2014 +++ +++ FCI 12 Charging: -Contact +++ +++ 3 22-10-2014 FCI 13 Charging: -Friction(Rubbing) Ebonite Glass Wool 22-10-2014 FCI Cloth 14 Charging: 3-Induction 2 1 22-10-2014 FCI 3 15 Coulomb`s Law + + K= 8.89 x109Nm2/C2 r 22-10-2014 FCI 16 Coulomb`s Law (N) Ɛo- Another constant called permittivity of vacuum 22-10-2014 FCI 17 Coulomb`s Law Several Charges y +q 1 F 13 F F 13 +q 2 +q 3 X F 23 F 23 22-10-2014 FCI 18 Electric Field Force acting on a unit positive charge at the point. q +++ (N/C) r 22-10-2014 FCI 19 Electric Field Force acting on a unit positive charge at the point. q +++ (N/C) r 22-10-2014 FCI 20 Lines of Force Point Charge - + positive 22-10-2014 FCI negative 21 Lines of Force Dipole 22-10-2014 FCI 22 Lines of Force Two positive charges 22-10-2014 FCI 23 Lines of Force Charged plane +q 22-10-2014 -q FCI 24 Lines of Force Two charged plates -q 22-10-2014 FCI +q 25 More Coulomb’s Law kq1q 2 F12 2 rˆ12 r12 ˆ12 r r12 r12 +q1 rˆ12 +q2 r12 F12 r12 Coulomb’s constant: permittivity of free space: Charge polarity: 22-10-2014 2 N m2 1 9 Nm k 8.988x10 9.0x10 2 C2 C 4o 2 1 C o 8.85x1012 4k N m2 9 Same sign Opposite sign Force is right Force is Left Electrostatics --- Charges must be at rest! FCI 26 Superposition of Forces F0 F10 F20 F30 .... r10 +Q1 r20 +Q2 r30 +Q3 F30 F20 +Q0 F10 kq 0q1 kq 0q 2 kq 0q3 F0 2 rˆ10 2 rˆ20 2 rˆ30 .... r10 r20 r30 N q1 q3 q2 qi F0 kq 0 2 rˆ10 2 rˆ20 2 rˆ30 .... kq 0 2 rˆi0 r20 r30 i 1 ri0 r10 22-10-2014 FCI 27 Zero Resultant Force, Example Where is the resultant force equal to zero? q1 = 15.0 mC q2 = 6.0 mC The magnitudes of the individual forces will be equal Directions will be opposite Will result in a quadratic Choose the root that gives the forces in opposite directions 22-10-2014 FCI 28 Electrical Force with Other Forces, Example The spheres are in equilibrium Since they are separated, they exert a repulsive force on each other Charges are like charges Proceed as usual with equilibrium problems, noting one force is an electrical force 22-10-2014 FCI 29 Electrical Force with Other Forces, Example cont. The free body diagram includes the components of the tension, the electrical force, and the weight Solve for |q| You cannot determine the sign of q, only that they both have same sign 22-10-2014 FCI 30 More Field Lines 22-10-2014 Q dq A dA Surface Charge Density: Volume Charge Density: Q dq V dV FCI 31 Superposition of Fields EP E1P E2P E3P .... r10 +q1 E 30 E 20 r20 +q2 r30 +q3 P E10 kq3 kq1 kq 2 E P 2 rˆ10 2 rˆ20 2 rˆ30 .... r10 r20 r30 N q1 q3 q2 qi E P k 2 rˆ10 2 rˆ20 2 rˆ30 .... k 2 rˆi0 r20 r30 i 1 ri0 r10 22-10-2014 FCI 32 Superposition Example Find the electric field due to q1, E1 Find the electric field due to q2, E2 E = E1 + E2 Remember, the fields add as vectors The direction of the individual fields is the direction of the force on a positive test charge 22-10-2014 FCI 33 Gauss’s Law The total of the electric flux out of a closed surface is equal to the charge enclosed divided by the permittivity. Gauss's Law is a general law applying to any closed surface. 22-10-2014 FCI 34 Gauss' law permits the evaluation of the electric field in many practical situations by forming a symmetric Gaussian surface surrounding a charge distribution and evaluating the electric flux through that surface. 22-10-2014 FCI 35