B1771 - ELETTROMAGNETISMO E OTTICA

Learning outcomes

At the end of the course, the student possesses basic knowledge of electromagnetism in vacuum and in material media, as well as the fundamentals of geometric, refractive, and diffractive optics. They have learned some concepts of vector field analysis and are capable of applying general concepts and fundamental laws to solve problems.

Course contents

Prerequisites.

Attending the General Physics 1 course (classical mechanics and thermodynamics) is essential to be able to follow this course profitably.

Electrostatics.

Properties of electric charge: invariance, conservation, quantization. Notes on the limits of application of the classical theory of electromagnetism. Coulomb's law, Gauss theory and their equivalence. Examples and classroom experiences: the torsion pendulum and the derivation of Coulomb's law. Triboelectric effects. Energy of an electric charge system. Electric field (static) and its properties: conservatism and superposition principle for the electric field. Electric field potential and its unit of measurement (volt). Examples of simple electrostatic potentials: straight and flat wire with uniform distribution of electric charge, dipole. Examples and classroom experiences: Visualization of electric fields. Electrical discharges in gas. Cathode ray tube. The cohesive energy of NaCl. Arrangement of atoms in a crystalline solid. Electrostatic attraction of water. Conductors and insulators. Electric field and potential at the surface and inside an electrical conductor. Continuous distributions of charges. Energy density of the electric field. Electrical capacity and its unit of measurement (farad). Calculation of the capacity of flat and parallel plates, of a sphere, of a pair of concentric spheres. Scientific and technological applications of the electrical capacity of a conductor. Examples and classroom experiences: photoconductive Selenium. Fast memory. Radio tuning. Gradient and its mathematical properties. Derivation of the electric field from the potential. Divergence and rotor of a vector field. Gauss's law in punctual form. Rotor of an electrostatic field. Examples and classroom experiences: evaluation of the best path. Analogy with hydraulics.

Charges in motion.

Electric currents. Current density. Mathematical expression of charge conservation. Stationary currents. Definition of ohmic conductor. P. Drude's model for conduction in metals. The discoveries of L. Galvani and A. Volta. Voltaic pile. Mentions of electrical circuits and Kirkhoff's laws. Examples and classroom experiences: Pb/PbO2 stack and Weston stack. Fuel cell. Non-ohmic conductors. Current pulses along the cells of the nervous system.

Magnetic field.

Forces between current-carrying wires. Lorentz force. Field of moving electric charges. The magnetic field as a relativistic effect. Equivalence between magnets and current-carrying circuits. Recall of special relativity. Time dilation and length contraction. Laws of Ampere, Biot and Savart, Laplace. Derivation of simple forms of magnetic fields: straight wire, circular loop, solenoid. Energy density of the magnetic field. Examples and experiences in the classroom: the Oersted experiment. Visualization of electromagnetic waves as a perturbation of the electric (and magnetic) field. Rotating disk and its effect on a magnet. The magnetic field does not do work.

Electromagnetic induction.

The discovery of Michael Faraday. Magnetic field flux and Lenz's law. Non-conservative electric fields. Mutual inductance and self-inductance for electrical circuits. Maxwell's equations. Discovery of the nature of light and electromagnetic waves. Examples and classroom experiences: Eddy currents. Induction of current in a circuit. Non-contact dynamo. Electric motor. Electric generator. DC or AC networks and current warfare. Who does the work?

Electric fields in matter.

Electric dipole at the molecular level. Force acting on an electric dipole. Induced dipoles and intrinsic dipoles. Polarization in matter. Effect of a dielectric on the capacitance of conducting materials. Free charges and bound charges. The auxiliary field D and its (in)usefulness. Examples and classroom experiences: Birefringence in the Icelandic Spate (Calcite). Quartz and piezoelectric transducers.

Magnetic fields in matter.

Magnetic properties of matter: diamagnetism, paramagnetism and ferromagnetism. Magnetic dipole moment. Force acting on a magnetic dipole. Magnetization of matter. Free currents and bound currents. The auxiliary field H. Notes on magnetic domains. Magnetic hysteresis curves. Forces between permanent magnets. Examples and classroom experiences: Forces acting on diamonds and paramagnets by a ferromagnet. Magnetic levitation.

Optics

Waves and their characteristics: amplitude, frequency, wavelength, phase. Plane, progressive and stationary waves. Examples and classroom experiences: generation of waves with the spring. Electromagnetic waves and their general characteristics. Poynting vector and electromagnetic energy flow.

Readings/Bibliography

One of the following texts

1) Edward M. Purcell and David J. Morin

Electricity and Magnetism Third Edition

Cambridge University Press

ISBN: 978-1-107-01402-2

2) Corrado Mencucci, Vittorio Silvestrini

Fisica Elettromagnetismo e Ottica

Editore CEA

ISBN:978-88-08-18661-4

3) Giancoli Fisica 2 (seconda edizione)

Editore CEA

ISBN: 978-88-08-18390-3

4) S. Focardi et al.

Fisica generale Elettromagnetismo 2a edizione

ISBN: 978-88-08-32015-5

Editore CEA

Teaching methods

Classic lessons on the blackboard with presentation of the topics. Classroom exercises and demonstrations. In addition viewing and discussion of scientific images and videos.

Assessment methods

The learning assessment consists of a written test and an oral interview. The ability to solve simple written exercises on the course topics is a condition for passing the exam.

Office hours

See the website of Enrico Gianfranco Campari