OBIETTIVI E CONTENUTI

OBIETTIVI FORMATIVI

L'insegnamento ha l'obiettivo di fornire gli strumenti essenziali alla comprensione dei fenomeni elettromagnetici e alle innumerevoli applicazioni pratiche dei campi elettromagnetici.

OBIETTIVI FORMATIVI (DETTAGLIO) E RISULTATI DI APPRENDIMENTO

L’insegnamento si propone di fornire strumenti teorici necessari alla comprensione di fenomeni quali l'interazione dei campi elettromagnetici con la materia e la propagazione ondosa. L’obiettivo primario è quello di instillare la sensibilità sull’importanza degli effetti dei campi elettromagnetici sulla materia, in termini di forze, energia e momenti, e sulle conseguenze di tali effetti, in termini di condizioni al contorno, attenuazioni, riflessioni. ecc., nell'ottica di preparare l'allievo ingegnere alla comprensione del funzionamento di dispositivi di interesse per le applicazioni quali le antenne o gli strumenti
di diagnostica di strutture o corpi biologici.

MODALITA' DIDATTICHE

Le lezioni e gli esercizi vengono svolti in aula dal docente.

PROGRAMMA/CONTENUTO

1. Course organization, motivation and applications (1.5; 1.5)
2. Some comments on Newtonian, relativistic and quantum physics; the role of classical relativistic electrodynamics in modern physics; some links between classical relativistic and quantum electrodynamics in simple cases; some properties of photons; number and properties of photons involved in many engineering applications (3; 4.5)
3. Recalling some prerequisites: Lorentz force; different models for electric charge distributions; electric current and electric current density; conservation of charge; Maxwell's equations in the presence of charges in vacuum in integral form (2.5; 7)
4. Exercises related to scalar and vector fields, circulations, fluxes, differential operators, international system of units (for electromagnetic quantities); fundamental equations in the presence of charges in vacuum in differential form (3; 10)
5. Electromagnetic fields in the presence of ponderable media:
   1. Some considerations on the constituents of matter (0.5; 10.5)
   2. Drawbacks of the approach based on the microscopic Maxwell's equations and the need for macroscopic quantities and relationships among them (0.5; 11)
   3. Conduction current: charge carriers; carrier concentration; its value in solids (conductors, semiconductors, insulators), liquids (electrolytes), gases (e. g., ionosphere, plasma); convection currents; conduction currents in the presence of a single family of carriers; different contributions to the velocity of carriers: thermal, diffusion and drift velocity; Fick's first law; diffusion coefficient; carrier drift; carrier drift in the presence of an electric field; carrier mobility; some important values for the carrier mobility; effects of the temperature on the mobility and on carrier concentration; conductivity; its values in most important materials; unit of measures; first simple constitutive relation for the current density; ideal insulators; superconductors and perfect electric conductors; conduction current in the presence of more families of carriers (1.5; 12.5)
   4. Electric and magnetic dipoles; electric and magnetic dipole moments; models for electric and magnetic polarizability; electric polarization, electric displacement, magnetization and magnetic field (4.5; 17)
   5. Final form of Maxwell's equations (integral and differential forms); macroscopic fields; displacement current (3; 20)
6. Exercises: other integral forms for Maxwell's equations; importance of curl and divergence equations; time-harmonic Maxwell's equations (3; 23)
7. Constitutive relations for ponderable media: linear-non linear; isotropic-anisotropic; dispersive-non dispersive in space and time; homogeneity-inhomogeneity in space and time; examples; integration of time-harmonic Maxwell curl equation and constitutive equations for linear, stationary and spatially non-dispersive media; effective permittivity (3; 26)
8. Boundary conditions at interfaces between different (motionless) media (3; 29)
9. Poynting's theorem: extension to electromagnetic phenomena of the principle of energy conservation (3; 32)
10. Exercises: exchange between electromagnetic energy and mechanical or thermal energy; Nichols' disk; Joule effect in a cylindrical conductor (2; 34)
11. Poynting theorem for time-harmonic fields (2; 36)
12. Exercises: power losses due to Joule effect and to dielectric losses; thermal effects in microwave ovens; field amplitudes radiated by isotropic antennas in a lossless and homogeneous medium (3; 39)
13. Conservation of momentum in the presence of charged particles and electromagnetic fields; a comment on the conservation of the angular momentum (2; 41)
14. Uniqueness theorem for the electromagnetic field: general case and time-harmonc case (3; 44)
15. Relevance of the wave equation for electromagnetic fields: plane and spherical waves (3; 47)
16. Electromagnetic plane waves (3; 50)
17. Monochromatic plane waves; wavelength, wavevector, polarization of time-harmonic vectors and vector fields (3; 53)
18. Propagation of plane waves in the presence of absorption: low loss dielectric media and good conductors; attenuation; skin depth; velocity of propagation; some comments on the effects of dispersive media (3; 56)
19. Reflection and transmission of a monochromatic plane wave at a plane interface: case of orthogonal incidence (2; 58)
20. Reflection and refraction of plane electromagnetic waves at a plane interface between different media (qualitative description) (1; 59)
21. Some comments on lumped-element circuits; distributed element circuits (3; 62)

TESTI/BIBLIOGRAFIA

• S. Bobbio, E. Gatti, Elementi di elettromagnetismo, Bollati Boringhieri, 1991
• G. Conciauro, L. Perregrini, Fondamenti di onde elettromagnetiche, McGraw-Hill, 2003
• J. D. Jackson, Classical electrodynamics, Wiley, 1999
• D. Pescetti, Elettromagnetismo, Piccin, 1985

DOCENTI E COMMISSIONI

Commissione d'esame

MIRCO RAFFETTO (Presidente)

GIAN LUIGI GRAGNANI

MATTEO PASTORINO

ANDREA RANDAZZO

LEZIONI

Orari delle lezioni

CAMPI ELETTROMAGNETICI

ESAMI

MODALITA' D'ESAME

L'esame orale si compone di tre domande: almeno una di carattere teorico e almeno una formulata come un esercizio.

MODALITA' DI ACCERTAMENTO

Al termine dell’insegnamento lo studente dovrà dimostrare di di aver appreso i principi di base che regolano l'interazione elettromagnetica con la materia a livello macroscopico e di essere in grado di affrontare e risolvere problemi non troppo complessi in tale contesto.

Calendario appelli