# 19704 - General Physics B

### Course Unit Page

• Teacher Laura Fabbri

• Credits 6

• SSD FIS/01

• Language Italian

• Campus of Forli

• Degree Programme First cycle degree programme (L) in Mechanical Engineering (cod. 0949)

Also valid for First cycle degree programme (L) in Aerospace Engineering (cod. 9234)

• Course Timetable from Feb 21, 2022 to May 30, 2022

### SDGs

This teaching activity contributes to the achievement of the Sustainable Development Goals of the UN 2030 Agenda.   ## Learning outcomes

At the end of the course the student has assimilated and is able to apply the knowledge on the basic concepts of the General Physics in the language of the Mathematical Analysis, of the Integral and Vector Calculus; he has assimilated and is able to apply the technical-scientific methodology needed in order to face in quantitative terms the physics problems.

## Course contents

1. Electrostatics. The 4 fundamental forces of the nature: gravitational interaction, weak interaction, electromagnetic interaction, strong interactions. Matter particles: quark and leptons. Interaction particles: bosons. Triboelectricity, lightning and thunderbolts. The principle of superposition. Continuous distributions of electric charge. The electric field. Electric field representation by means of field lines. The flux of the electric field. The Gauss law for the electric field. Divergence of a vector field. The Gauss theorem (or divergence theorem). Local form of the Gauss law for the electric field. Electrostatic potential.
2. Conductor electrostatics. Dielectrics and conducting media. Charge distribution, electric field and potential inside conductors. Electrostatic induction. Electric field on conductor surface. Electric field in a cavity inside a conductor, electrostatic screen, Faraday cage. Complete induction. The meaning of grounding. Potential of a charged conducting sphere. The power of points. Conductor capacity. Capacitors and their capacity. Capacitors linked in series and in parallel.
3. The general problem of the electrostatics. Electrostatic energy of a point charge system. Electric dipole. Electrostatic energy of a charged capacitor. Electrostatic energy density associated with an electric field. Localization of the electrostatic energy. Locality of the energy conservation principle. Poisson and Laplace's equations. The general problem of the electrostatics.
4. Electric current. Electric current, Drude-Lorentz model, drift velocity and thermal velocity of the conduction electrons.current strength and current density. Ohm's law in the integral and local form, resistance, conductance, resistivity and conductivity. Resistors. Resistors linked in series and in parallel. Dissipated power, Joule's law. Superconductors. Electric generators. Non-electrostatic and non-conservative characteristic of the forces that move the electric charges in an electric generator. The Van der Graaf's generator. Direct-current circuits. Long-distance power lines: use of high voltages to reduce the power dissipation. Transient in a RC-circuit: charge and discharge of a capacitor.
5. Magnetic force. The interaction between two charged particles in uniform motion. Ampère-Biot-Savart law. Magnetic force and its characteristics. Continuous distribution of charge in motion. Local conservation of the electric charge, continuity equation in integral and local form. The magnetic field, Lorentz's force, magnetic force on a continuous distribution of charge in motion due to a magnetic field, magnetic field generated by a continuous distribution of charge in motion. Electric wires, first and second Laplace's formulae, Biot-Savart law, magnetic field generated by a circular loop and by a solenoid. Force between two rectilinear electrical wires. Definition of the Ampère unit.
6. The equations of the magnetic field. Tubes of flux. Flux of the magnetic field. Gauss law for the magnetic field in integral and local form. Absence of the magnetic charge. Circulation of the magnetic field. Ampère-Maxwell's law in integral and local form. Maxwell displacement current. Ampère-Maxwell's law and conservation of the electric charge. Calculations of magnetic fields using the Ampère-Maxwell's law: indefinite rectilinear electric wire, solenoid.
7. Electromagnetic induction. Null flux non-conservative electric fields. Circulation of the electric field. Faraday-Lenz's law in integral and local form. Induced electric field, electromotive force and induced current. The Maxwell's equations.
8. Electric circuits. Self inductance. Inductance of a solenoid. Energy accumulated in a solenoid covered by a stationary electric current. Energy density associated to a magnetic field. Mutual inductance. Transformers. Mean value and root-mean-square value (effective value). Alternate current. Galileo Ferrari's formula. Circuit elements: resistors, capacitors, inductors and electromotive force generators. Electric networks, Kirchhoff's laws and Maxwell's rule. Transient in a RL-circuit. Extracurrents. Oscillating RLC-series circuit: analogy with the mechanical damped oscillator. The complex formalism. Stationary state of a RLC-series circuits submitted to an alternate electromotive force. Impedance, resistance, reactance, admittance, conductance and susceptance.
9. Electromagnetic waves. Density of the energy flux, Poynting vector. Energy conservation and Poynting theorem. Electromagnetic waves, d'Alambert's equation. Solutions of the d'Alambert's equation: plain progressive and regressive waves, spherical converging and diverging waves. Transversality of the electromagnetic waves. Relation between the electric and the magnetic field in an electromagnetic wave. Linear, circular and elliptic polarization. Right-handed and left-handed polarization. Non-polarized and partially polarized electromagnetic waves. Method of polarization of the electromagnetic waves: selective emission, selective absorption, single scattering and reflection. Perfect polarizer. Malus's law. Brewster's angle. Birefringent plates. Application: anti-glare glasses, liquid crystals.
10. Thermodynamic systems and molecular motions. Extension of the principle of energy conservation to dissipative forces: internal energy. Kinetic molecular theories. Relations between macroscopic thermodynamic quantities and microscopic mechanical quantities. Microscopic mechanical reversibility and macroscopic thermodynamic irreversibility. Free expansion of a gas and spontaneous compression: Poincaré's time. Intensive and extensive quantities. Thermodynamical equilibrium. Adiabatic and diathermic walls. Thermal contact. Thermal equilibrium between two thermodynamical systems. Thermometers: thermometric materials, thermometric properties and thermometric functions. Zeroth law of thermodynamics. Thermometer calibration. Fixed points: normal melting point, normal boiling point and triple point. Ideal gas thermometer. Units of measurement of the temperature. International temperature scale. Thermodynamic transformations. Quasi-statics thermodynamic processes. Clapeyron diagram. Adiabatic quasi-statics thermodynamic processes of a gas. Quasi-statics isochoric heating and cooling of a gas. Equation of state of an ideal gas. Mole and Avogadro's number. Atomic mass and molecular mass: the unified atomic mass unit. Isothermal processes of real fluids. Critical temperature. Saturated vapor pressure. Changes of the aggregation state. Van der Waals equation: co-volume and internal pressure constant. Ebullition. Bubble chambers.
11. First principle of the thermodynamics. Average molecular kinetic energy. The work in a quasi-static transformations of a fluid. Adiabatic work. Internal energy. Amount of heat. The first principle of the thermodynamics. Heat capacity, specific heat and molar heat. Latent heats. Ideal gases. Technical work and enthalpy. Property of ideal gases. Quasi-static adiabatic transformations of an ideal gas: Poisson's formulae.
12. Second principle of the thermodynamics. Reversible and irreversible transformations. Heat engines. Efficiency of a heat engine. Carnot's cycle. Refrigerating systems. Second principle of the thermodynamics: Kelvin-Planck and Clausius statements and their equivalence. Impossibility of the perpetual motion of first and second species. The Carnot's theorem. Absolute thermodynamic temperature. The Clausius's theorem. Entropy. The law of the increase of the entropy. Example of calculations of entropy variation in a reversible or irreversible thermodynamic process. The equation of the internal energy. The equation of the enthalpy. The equations of the TdS. Helmholtz and Gibbs's thermodynamic potentials and their properties.

• Copy of the transparencies presented during the course and the digital boards, available on World Wide Web at the Alma Mater Digital Library: Virtuale
• Question and exercises for the assessment, available on World Wide Web at the at tthe Alma Mater Digital Library: Virtuale
• Focardi, Massa, Uguzzoni, Fisica Generale, Elettromagnetismo, Casa Editrice Ambrosiana, Milano.
• Focardi, Massa, Uguzzoni, Fisica Generale, Onde e Ottica, Casa Editrice Ambrosiana, Milano.
• Amaldi, Bizzarri, Pizzella, Fisica Generale, elettromagnetismo, relatività, ottica, Zanichelli, Bologna.
• Feynmann, Leighton, Sands, The Feynmann Lectures on Physics, vol II, Addison-Wesley.
• Rosati, Casali, Problemi di Fisica Generale, volume 2, elettricità, magnetismo, elettrodinamica e ottica, seconda edizione, Casa Editrice Ambrosiana, Milano.
• Salandin, Pavan, Problemi di Fisica risolti e commentati, volume 2, Casa Editrice Ambrosiana, Milano.

## Teaching methods

• During the frontal lessons blackboard/tablet is used and slides or multimedia are shown by means of a projector.
• Such transparencies are made available to the students before the lecture by means of World Wide Web VIRTUALE, in order to reduce the time and the work of mere transcription during the lessons and as in-depth study.
• The proposed practices demand the use of the pocket calculator.
• To communicate with students, the mailing list [https://www.dsa.unibo.it/] of University Directory Service is widely used as well as the forums provided by the VIRTUALE website.

## Assessment methods

• The assessment of the achieved learning outcomes in the Integrated Course of General Physics (I.C.) consists in two distinct exams, which may be taken in different days (in the same Academic Year) or in the same day: the exam of the module of General Physics A and the exam of the module of General Physics B.
• The module-exam for both the modules (General Physics A and General Physics B) is written and consists in questions and exercises concerning the topics introduced during the lectures, with the aim of verifying that the student has deeply understood the physics principles and is able to apply them in formulating the laws which regulate specific physical phenomena.
• The students are required to choose the right answer in a list of chances; to the right answer corresponds a score of +1 point, while each of the wrong answers carries a negative mark of -1/(number of wrong answers).
• In the exercises, the students have to report the numerical values of the required quantities, expressed in the proposed units of measurement, showing familiarity with the rules of dimensional analysis and the ability to perform numerical calculations with the necessary approximation; the evaluation is based on the accuracy of the reported values.
• The pass of the module-exam requires a rating of 18/29 or higher.
• The maximum mark for the written examination is 29. An additional 3 points can be obtained by passing the "exam preparation tasks" available on the VIRTUAL page of the course (https://virtuale.unibo.it/course/view.php?id=17954). Passing each of the three tasks entitles the student to an additional mark.
• Preparation tasks can be taken online at any time before to the exam date and can be repeated at pleasure until the the task is passed. The preparation tasks draw on the same database of exercises used to build the exam task.
• Full marks with distinction (laude) is attributed to a module-exam grade if the student demonstrates an excellent preparation by achieving the maximum score (32/30).
• The global exam of the Integrated Course of General Physics (I.C.) is passed if both the module-exams (General Physics A and General Physics B) are passed.
• In case of global exam pass, the grade is the mean value between the grades of the two module-exams (General Physics A and General Physics B).
• Full marks with distinction (laude) is attributed to the global exam grade if both module exams (General Physics A and General Physics B) has been passed with distinction.
• The teacher reserves the right to test the preparation by means of an oral interview.
• Further details about the exam tests and their evaluation are available at the VIRTUALE web page.

## Teaching tools

Blackboard, Projector, Laptop

## Office hours

See the website of Laura Fabbri