1,720,993 research outputs found
Capacitance and potential coefficients at large distances
No full textThe design of capacitive sensors and devices for new and emerging applications would benefit from simple and reliable methods to estimate the capacitance between conductors in terms of the capacitance of the isolated bodies and of the distance between them. The coefficients of potential and capacitance of a pair of conductor are approximated with the first terms of an expansion formula in the inverse of their distance. The form given applies to conductors of generic shapes and position in space. A comparison with the exact value for two spheres shows agreement even for rather small distances
Some comments on the electrostatic forces between circular electrodes
No full textWe study the force between two circular electrodes in different configurations. A formula analogous to Kelvin's formula for the spheres is given in the case of equal disks held at the same potential and when one plate is earthed. An expression for the force at short distance between two arbitrarily charged disks is found: the generic case shows a logarithmic repulsive force, also for disks carrying charges of opposite sign. Some numerical computations support the results. A classification for the possible behaviors of the force is proposed on the basis of a decomposition of the capacitance matrix. It is shown that the forces depend strongly on the dimensionality of the contact zone between the conductors. The analysis is supported by a numerical computation carried for the case of two disks of different radii
Topics in Radiofrequencies and Laser Spectroscopy
No full textIl volume è un tributo scientifico ad Adriano Gozzini (1917-1994) in occasione del 20° anniversario della sua scomparsa. Pioniere della spettroscopia molecolare delle microonde, del pompaggio ottico e della spettroscopia laser, Gozzini è stato uno dei maggiori protagonisti del secolo scorso nel campo della fisica atomica.
Il volume riproduce 20 articoli scritti da Adriano Gozzini, tra cui un preprint inedito, scelti per fornire un quadro completo dei diversi argomenti affrontati dallo scienziato nell'arco della sua carriera scientifica. A ogni articolo è associato il commento di scienziati che con lui hanno collaborato o di esperti internazionali sul tema trattato, tra i quali i Premi Nobel C. Cohen-Tannoudji, T.W. Haensch e S. Haroche
The account of a lifetime
No full textThe book is a scientific tribute to Adriano Gozzini (1917-1994) on the occasion of the 20th anniversary of his death. Pioneer of molecular spectroscopy of microwave, optical pumping and laser spectroscopy, Gozzini was one of the leaders of the last century in the field of atomic physics.
The book reproduces 20 articles written by Adriano Gozzini, including an unpublished preprint, chosen to provide a complete picture of the different topics addressed by the scientist during his scientific career. Each item is associated commentary by scientists who have collaborated with him or international experts on the subject matter, including Nobel laureates C. Cohen-Tannoudji, T.W. Haensch and S. Haroche
Measuring light speed with a modulated laser diode
No full textAbstract. The time of flight (TOF) of a light pulse travelling back and forth and optical path length measurements are used to estimate the velocity of light. The light pulse has a duration of 10 ns, and is obtained from a suitably modified CW commercial laser diode. The TOF is read with a digital oscilloscope connected to two fast sensors, detecting the signals at the switch-on of a laser diode and at the arrival of the light pulse reflected from a plane mirror placed at a known distance
Capacitance and forces for thick circular electrodes
No full textSome new results are presented concerning the forces between two equal circular electrodes of finite thickness. For close electrodes different scenarios result, depending on the thickness and on the ratio of charges of the conductors. Attractive or repulsive forces can appear depending on the parameters and on the separation of the electrodes. The force between the electrodes can be non monotonic as a function of the distance and one or more equilibrium points can appear. A unified description of cylindrical systems using a high precision method based on a Galerkin expansion is given and we check our results with a quite accurate boundary element method (BEM)
Capacitance and forces for two square electrodes
No full textA numerical and semi-analytical study of electrostatics of a system of two parallel square electrodes is focused on the behavior at short and large distances of the capacity coefficients and of the electrostatic forces between the plates. It is found, using a Boundary Element Method approach with a regular grid and an analytical treatment of the kernel matrix, a strict parallelism with the analogous system of two circular disks, in particular for the possibility of disentangle the divergences at short distances and the presence of a logarithmically divergent repulsive force, with the exception of electrodes with exactly opposite charges. With our semi-analytical approach, fully exploiting the symmetries of the problem and using very small subdomains, the capacitance coefficients of the two square capacitor are determined with a great accuracy, comparable with the best data available in the literature just for the capacitance of a single square
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