PHYSICS LABORATORY 3 (UNIT 1)
Learning outcomes of the course unit
At the end of the course the student is expected to be able to:- To understand the basic concepts of modern physics. (1st Dublin descriptor)- To acquire awareness of the different degrees of difficulty involved in designing and performing a new experiment. Addressing and solving the problems that might arise. (2nd descriptor of Dublin)- To develop a sensitivity to assess the most appropriate experimental techniques, as well as the size orders of the variables in play. (3rd descriptor of Dublin)- To produce a written report that analytically and critically portrays the progress and results of a simple experiment. To treat orally the same topics. (4th Dublin descriptor)- Learn how to conduct experiments autonomously. (5th Dublin Descriptor)
Laboratorio di Fisica 1,
Laboratorio di Fisica 2
Course contents summary
This course offers to the students, almost at the end of their undergraduate training, a series of experiences, some of them being related to the birth of "Modern Physics", others related to current research themes.The detailed program is available on the ELLY platform.
The available experiments are listed on the ELLY portal, together with the corresponding handouts. The following is just a static summary.
- Millikan: classic experiment presented in didactic version, allows you to calculate with a certain approximation the value of the elementary electric charge.
- photoelectric effect: classic experiment in didactic version, allows to observe the particle nature of electromagnetic radiation and you to measure Planck's constant, known spectral lines of the mercury source and the value of the elementary charge.
- Thomson: classic experiment in didactic version, to evaluate the relationship and / or m "specific charge" of the electron.
- Franck-Hertz: the classic experiment in didactic version, further automatedto see the quantization of energy levels. This experiment also provides an example of non-conventional spectroscopy.
- visible black body: you will have to measure the intensity of light emitted by a black body temperature of between 800K and 3300K. In a second step, dealing with different experimental difficulties, it will then be possible groped to characterize the spectral curve (Planckian) in the range of wavelengths from visible to near infrared.
- UV-vis absorption spectroscopy: Students become familiar with the spectrophotometer and its limits by verifying the law of Lambert-Beer. Later you can run several experiments on kinetics of evolving physical systems (diffusion of ions in solution, molecular photoisomerization, etc.).
- Fluorescence spectroscopy: we study the fluorescence of a fluorophore in function of its concentration, highlighting the different regimes. It is strongly it recommended that you have already done the experience of the UV-visible absorption spectroscopy.
- Brownian motion: measurement of the thermal agitation of colloidal particles of micrometer size suspended in water (relevant properties to a file in the archive of educational materials) through an optical microscope, digital camera and PC used in Matlab environment. Measured mean square displacement of particles as a function of elapsed time, through the analysis of Einstein, it is possible to derive an estimate of Avogadro's number.
- LCD: students, once familiar with the polarizing optical microscope, the observed birefringence of the behavior of some crystalline and / or polymeric liquid systems, as a function of temperature and applied electric field in a cell that will 'was from them to' built purpose.
- Measurement of viscosity in a transition of gelation. Via a torsion pendulum, machine-readable that students will have to develop and optimize, we will measure the viscosity of some solutions that gel.
- Measurement of percolation transition in a granular mixture similar to a fractal: it is a transport measure in a granular medium. Measuring the electrical conductivity (DC or AC, with 2 or 4 points) in a series of pads prepared by mixing a conductive powder (Cupper) and an insulator in varying proportions.
Handouts are available for all the experiences, on the ELLY platform which also hosts the manuals for all the instruments to be used Original papers (e.g. by Millikan, Einstein, Perrin) are provided on the same platform, as a further stimulus.The following texts (available in our Library) focus on themes of particular interest, and can be useful to the curious student:- Horowitz and Hill. The Art of Electronics, Cambridge University Press- R.A.L. Jones Soft Condensed Matter. Oxford University press
The course begins with lectures common to all students, to outline the conceptual basis of the experiments available, highlighting the possible experimental difficulties and measures to overcome them.
Handouts are uploaded on the Elly portal by the teacher at the beginning of each academic year.
Then the laboratory sessions follow, where students, in groups of 2 or 3, do 2 or 3 experiments.
Active participation of the student in the laboratory experiences is an essential part of the course, as well as of the evaluation path.
In the presence of special conditions (for example, in the case of working students) personalized timings/ courses can be planned.
Assessment methods and criteria
Evaluation of this 1.st module consists in a colloquium focused on the reports of the experiments performed by each student. This colloquium is typically in February, while a 2.nd colloquium, for the 2.nd modulus, is held typically in the summer session.
The final score for the course is the average of the scores of the two colloquia.
For the analysis of the experimental data it is strongly recommended that students know how to use Matlab.
For some experiences it is necessary to use a minimum of electronic instrumentation for the acquisition of signals, such as a computer with a data acquisition card (ADC).
Some experiences require digital acquisition and processing of films and images and / or microimages. The Matlab procedures for extracting quantitative information from images are described in a tutorial provided in the archive.
Students are encouraged to keep a "log book" accurate and updated, to write down all observations which may serve to describe or to repeat the experiment. In addition, it is useful that each group will re-encounters in the course of the week discuss and / or seek clarification from the teacher, available on appointment also outside of laboratory time.