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.

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 dovra' dimostrare di aver assimilato gli strumenti essenziali alla comprensione dei fenomeni elettromagnetici

Calendario appelli