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You can see the previous offering of this course from Fall 2014 here.
Electricity and Magnetism
Instructor: Dr. [Sabieh Anwar]. Office hours are Tuesday 10 am to 12 pm. Recitations will be led by Mr. [Nauman Ahmad Zaffar].
Teaching Instructors:
See the schedule for tutoring sessions below.
Course outline: Click here for the course outline.
Schedule for Tutoring Sessions -- Fall 2015
Pre-mid term
To access the video recordings, click on the numbered links below.
Electric Fields (2 lectures)
- Electric charge, Coulomb's law, vector fields, electric field, superposing electric fields [1]
- Electric field due to distributed charges, electric dipoles, connection between electrostatic and mechanics problems, field due to a charged rod, charge disk [2]
Gauss's law (3 lectures)
- Electric flux, flux through a closed sphere concentric with a point charge, flux through arbitrary shaped surfaces and charge distributions [3]
- Formal statement of Gauss's law, using Gauss's law to determine electric fields (line, sheet of charge), role of symmetry, fields inside conductors; Demonstrations: Wimshurst machine and Gauss's law [4]
- Spherical symmetry, fields around and inside conductors, a charged metal ring enclosing an insulating sphere [5]
- Homework 1. This is a collaborative assignment. Work in groups of up to three. Due date is Wednesday,16 September 5 pm. Drop homework solutions inside the orange boxes in the Physics corridor. Solution.
Electric potential (3 lectures)
- Electric potential energy defined using first law of thermodynamics (energy conservation), potential energy of a system of charges, potential energy o a charge inside the field of a point charge [6]; Demonstrations: Ionic wind and corona discharge.
- Relation between electric field and electric potential, relation between electric potential and potential energy, potential due to a sphericaly symmetric distribution of charges, potential between parallel plates, a metal is an isopotential surface. [7]
- Electric potential due to series of parallel plates, coaxial conductor, dependence of potential on size, path independence of potential, line integral of electric field around closed paths [8]
Currents, batteries, semiconductors (5 lectures)
- Negative electric feedback explaining consistency of current through bent wires, dissimilar metals, graded conductors, motivating Kirchoff's current law [10].
- Surface charges enabling the flow of current in surface conductors, introduction to batteries Part A and Part B. There was an error in my description towards the end. The slope of the potential inside the battery is E/s instead of E and the potential rise is E instead of Es. Demonstrations: The resistance of a semiconductor drops with temperature.
- Classes of materials based upon conductivity, intrinsic and extrinsic semiconductors, band diagrams, PN junction and depletion layer [11].
- A holistic view of how a PN junction works, recombination and thermally assisted charge carrier generation, biasing a diode, field and potential landscape [12]
Mid-term
Midterm and its solution.
Post-mid term
Producing magnetic fields and moving charges inside magnetic fields (4 lectures)
- Moving charges produce magnetic fields, Oersted's discovery, Biot-Savart law, field due to an infinitely long wire, Ampere's law [13]. Demonstrations: Oersted's discovery.
- Charges move in circular orbits inside magnetic fields, combined magnetic and electric fields, example of the cyclotron, forces and torques on magnetic dipoles, energy of a magnetic dipole inside a magnetic field [15] . Demonstrations: Steering electron paths using magnetic fields inside a cathode ray tube.
- Forces between dipoles, fields due to sheets of current, reviewing in total electric and magnetic fields inside and around current carrying conductors [16].
- Homework 4. Due date is Thursday, 12 November 5 pm. This homework must be solved individually. Solution.
Magnetism inside matter (2 lectures)
- Atomic origins of magnetism, spin, Stern-Gerlach experiment, phenomenological classification of magnetic materials, relations between B, H and M, magnetic susceptibility [17]. Demonstrations: Forces on conductors inside magnetic fields.
Varying electric and magnetic fields and fluxes (5 lectures)
- Magnetic braking, domain wall pinning and Barkhausen effect, what is meant by a non-conservative field, induced emf, example of a wire close to another wire carrying a time-varying current [20]. Demonstrations: Magnetic braking.
- Moving magnets near a coil, solenoid carrying varying current placed near a pickup coil, uniform and non-uniform cross section pickup coils, superconducting coils and Meissner effect, skin effect, why diamagnetism, generator coil, shrinking ring in a uniform field [21].
- Motional emf, falling conductor inside a magnetic field, where is the power coming from, uniform magnetic fields cannot do work, Hall effect, origin of forces acting on current carrying conductors [22].
- Some nuances about the motional emf, fields and currents inside superconductors,homopolar generator, Maxwell-Ampere's law [23].
Some circuit elements (4.5 lectures)
- Capacitors, capacitance, charging and discharging (field description), capacitance of select geometries, energy inside electric and magnetic fields [24].
- Energy flow in a simple circuit, Poynting vector, "deriving" Ohm's law [26].
- Using Poynting vectors to describe energy inflow into a capacitor, two alternative ways of finding out the energy inside a capacitor, fields harbor energy, energy inside an inductor, what happens when a metal is placed inside a capacitor, polarizability of molecules [27].
- Homework 6. Due date is Monday, 14 December 5 pm. This is an individual homework and will be coarsely graded. Solution.
Electromagnetic waves (2 lectures)
- Dielectrics inside capacitors, relative permittivity, a possible field configuration for electromagnetic waves, speed of light [28].
- How are electromagnetic waves produced, accelerating charges, concept of radiation, EM waves transfering energy and momentum, Poynting vector seen again [29].
- Read Ch. 34 and attempt selected problems of Jewett and Serway's "Physics for Scientists and Engineers".