70/0005/E - PHYSICS 2/E

Academic Year 2021/2022

Free text for the University

Objectives

Knowledge of electrostatics and electrodynamics, and ability to solve practical problems involving DC and AC circuits, electromagnets, etc.

Prerequisites

Elements of calculus (derivatives, integrals, simple differential equations) and vector calculus. Elementary mechanics of point-like and rigid bodies. All the notions necessary are recalled in class. Material is provided on the site.

Contents

The e-course follows largely the same syllabus as the normal course, listed below.

1 - Electrostatics

Electric charge. Conductors and insulators. Coulomb’s law; electric field and field lines. Field generated by charge distributions. Flux of the electric field. Gauss’s law and first Maxwell equation. Applications to various charge distributions. Electrostatic potential and potential energy. Equipotential surfaces. Potential generated by charge distributions; potential and field in a conductor. Field-potential relationship and second Maxwell equation.

 2 - Capacitors

Capacity and capacitors. Flat, spherical, and cylindrical capacitor. Capacitors in series and in parallel. Energy density associated to the field in a capacitor. Capacitor with a dielectric medium. Polarization and dielectric response. Dielectric constant. Energy density in a dielectric-filled capacitor.

3 - Circuits

Current and current density. Microscopic model of conduction in materials. Resistance and conductance. Ohm’s law. Power, Joule effect and applications. Conductors, insulators, semiconductors. Electromotive force. Resistors in series e in parallel. Kirchhoff’s rules for circuits. RC circuits and their properties.

4 - Magnetic field in vacuum

Magnetic force and magnetic field. Solenoidal field and third Maxwell equation. Magnetic force on a current-carrying wire. Mechanical moment on a loop. Magnetic dipole moment generated by a current. Biot-Savart’s and Ampere’s laws. Field generated by an infinite wire, an infinite solenoid, and a toroid. Force between two parallel wires. Field-current relations and fourth Maxwell equation (Ampere version).

5 - Electromagnetic induction

Faraday-Lenz’s law, and completion of second Maxwell equation. Electromotive force in a moving loop; principle of the DC electric motor. Rotating loop and principle of the AC motor. Rowland’s disk and electromagnetic brakes. Mutual induction and self-induction. RL circuit: magnetic energy density.  LC circuit and oscillations. RLC circuit: damped oscillations and critical damping. RLC circuit with AC source: reactance, inductance, resonance; phasor formalism. Transformer, qualitatively.

6 - Maxwell equations and electromagnetic waves

Displacement current and Ampere-Maxwell’s law; completion of fourth Maxwell equation. Integral and differential form of Maxwell’s equations in vacuum. Derivation of the existence of electromagnetic waves.

Electromagnetic waves: properties, spectrum, propagation, generation. Transported energy, Poynting vector, intensity. Speed of light in vacuum and in matter. Radiation pressure. The origin of magnetic forces from electrostatics and relativity.

Teaching Methods

The course comprises about 18 video hours, plus abundant material, mostly pdf, concerning theory, exercises, maths, and more. Simulations of the final exam are alsoprovided in due course. There is a virtual class where exercises are discussed and corrected.

Verification of learning

The final exam is the same as the normal course. It is a single written exam, about 6 questions, 2 hours.

Texts

All the texts needed are provided on the course site.

More Information

The course site provides all the needed material. More exercises and solutions are also made available on the normal course site, http://people.unica.it/vincenzofiorentini/didattica/materiale-didattico/

Meet-up by appointment at Dipartimento di Fisica, Cittadella Universitaria.

People with DSA please see here: http://corsi.unica.it/ingegneriaelettricaeelettronica/info-dsa/