Elettricità e magnetismo

VISUALIZZA GALLERIA IMMAGINI

Aghi magnetici

Magnetic needles free to rotate in a horizontal plane; they allow to put into evidence the existence of the terrestrial magnetic field and to make tests concerning the interaction between magnetic poles.
Banco dell’Ampère

This device allows to study the electromagnetic behaviour of the current and permits to confirm the validity of Ampère ‘s theorem. The scientist built the first model of this appliance in 1820.
Apparato dell’Ampère per le correnti

This device is another example of Ampère’s bench.
Apparato per la legge di Oersted

The device allows to reproduce the famous experience the Oersted (1777 – 1851) in 1820.
Apparato per l’induzione

The device allows to study the phenomenon of electromagnetic induction discovered by Faraday. Any variation of magnetic flux chained with a circuit provokes in this an electromotive force for the time in which the variation of flux lasts.
Apparato per la danza elettrica

The device is also known as “ appliance for the electric hail” because of the hypothesis on the formation of hail carried out by A Volta.
Serie di archi scaricatori

A series of discharger arches used to discharge a condenser quickly.
Bottiglia di Leyda ad armature mobili su sgabello isolatore quadrato

The Leyda bottle, with mobile coil, is a condenser used to show the persistence of the polarization of an insulator. It takes its name from the city of Leyda where Cunaeus, Musschenbroek’s disciple, discovered its effects by chance during some lab tests in 1746.
Bottiglie di Leida a forma cilindrica di dimensioni diverse

The collection is made up by three couples of Leyda bottles of different dimensions. They are not all alike as for the composition of structural elements.
Bussola con scatola di legno

A device whose working system is based on the capacity of a magnetic needle, in a position of balance, always to indicate the South - North direction.
Bussola piccola con cerchio metallico graduato

A specimen of a late 19th century pocket compass with a brass case.
Bussola delle tangenti

The tangent compass, built by W. Weber in 1842 exploiting the working principle discovered by Pouillet (Cuzance 1791-Paris 1868) in 1837; it was the first instrument which allowed to measure the current absolute intensity. It is an example of the interaction between electricity and magnetism.
Bussola di declinazione

A compass that allows to measure the magnetic deviation angle of a place, that is the angle formed by the magnetic needle with the direction of geographic North.
Calamita permanente grande di kg. 20 e di portata Kg.50

Lamellar horseshoe magnet with an anchor made of four blocks of soft iron to increase its magnetic effects.
Soneria elettrica

An electric call-bell which represents a useful application of the electro-magnet.
Campanello elettrico con scatola di noce

It has the same construction and working characteristics of the electric bell, but it belongs to an earlier period.
Campanello elettrico

A specimen of electric bell.
Soneria pneumatica

A specimen of pneumatic ring.
Cellula fotoelettrica

The device, whose working system is based on the photoelectric effect, is used in photometry to measure the intensity of light sources, in telegraphy because it allows the far away transmission of images, in sound movie, in astronomy to establish the intensity of the light sent by the stars and to point out the moment when the star passes on the meridian, and as a signaller of several kinds.
Cilindri in ottone su asta di vetro

The devices, equipped with small metal leaves and pendulums, are used in didactic to analyse the phenomena connected with the electrostatic induction.
Commutatori a manovella

The device allows to interrupt or to establish a current in different circuits without taking the clamps out. There are two versions: one with five and one with three connection plates.
Commutatore per unire una serie di 12 elementi

A box of resistances conceived by the German builder of instruments W. Siemens (1823 –1883). The following inscriptions are engraved on the lid: “Patented May -7-1907”; “Central Scientific L. Chicago”.
Commutatore di Ruhmkorff

A commuter which allows to activate alternatively two circuits connected with the device itself.
Condensatore ad armature mobili

A condenser of variable capacity used in the fields of radio engineering and electronics.
Condensatore di Epino

Epinus’s condenser, invented by the German physicist Ulrich Theodor Aepinus (1724 – 1802), is an example of flat condenser; it is used to accumulate noteworthy amounts of charges on relatively narrow surfaces.
Condensatore piano

It is just a flat condenser. The device can be considered as a first specimen of Volta’s electrophorus.
Diapason elettromagnetico con microscopio

It is an electro-acoustic appliance that was rapidly widespread in all technical and scientific applications when it was necessary to produce a long running frequency, longer that the diapason normal extinguishing times.
Diapason da 100 vibrazioni

Tuning-fork with electro-magnet to record the vibrations, mounted on a metal column.
Dinamo ad armatura di Pacinotti-Gramme

The device is an electric generator that transforms mechanical energy into direct electrical current. The first generators were built between 1832 and 1835; Pacinotti improved them introducing a ring armature (Pacinotti’s ring). Z. Th. Gramme (1820-1901) built an industrial kind.
Dischi di metallo con manico di vetro

A series of metal discs, of different diameter, with non-conducting glass handles. They are used as accessories for electrostatic machines or devices.
Elettrocalamita con sostegno in ferro

This is an example of electromagnet furnished with an iron coil, which is also called ‘anchor’: if it is put near the extremes of the magnet itself, it increases greatly its attractive capacity. The discovery of the electromagnet is to be awarded to the French physician Andrè Marie Ampère (1775-1830).
Ferro di cavallo per elettrocalamita con sostegno di legno ed ancora

An example of horseshoe electromagnet, whose effect is increased by the contemporary action of the two near poles and by the presence of a metal slab, called “anchor”, that is an integral part of the apparatus.
Elettroforo del Volta con lamina di ebanite e fondo di zinco

The electrophore is a simple kind of electrostatic machine, invented by A. Volta in the second half of the 18th century. As we learn from a correspondence between Volta and Priestley, Volta himself suggests, for his own machine, the name of “perpetual electrophore” to point out how the shield may furnish charges for a long time without re-rubbing the basis.
Elettromagnete rotante con vaschetta di legno

The device, run through by electric current and fit between the expansions of a magnet, starts rotating, changing the direction of the current whenever the wires pass from one section to the other of the basin. The working system of the device is used in direct current electric engines.
Elettrometro a quadrante (a)

The device is a stiff pendulum electrometer; it allows to evaluate roughly the power of the electrostatic generator to which it is connected.
Elettrometro a quadrante (b)

A specimen of stiff pendulum quadrant electrometer, where some parts are missing.
Elettrometro condensatore del Volta

The condenser electrometer was invented by A. Volta as an alteration of the electroscope in order to measure the potential of a weakly electrified loaded body.
Elettroscopi a foglie d’oro

Devices used to find out the presence of electric charges and to state their sign.
Elettroscopio a pagliuzze

This device was invented by A. Volta (1745 –1827) towards the end of the 18th century as an alteration to some other similar ones which, instead of slivers, had some very light balls of elder marrow hanging from strings or extremely thin gold-leaves. The alterations Volta brought in had the purpose to make the measures of electrostatic charges comparable and recurring.
Emisferi di Coulomb

The apparatus, due to Coulomb, allows to show that the electric charges in a conductor, charged and in electrostatic balance, are distributed on the surface of the conductor itself.
Foravetro

The appliance, used for didactic purposes, permits to experiment the mechanical effects of the electric discharge through the breaking of thin glass layers.
Galvanometro del Nobili montato in ottone con sistema astatico

This kind of galvanometer was invented by Leopoldo Nobili (1784-1835) who, substituting the simple magnetic needle used up to that time with the astatic system, was able to reduce greatly the effect of the earthly magnetic field on the mobile equipment.
Galvanometro differenziale del Nobili montato in ottone

Anotherkind Nobili’s galvanometer.
Galvanometro moltiplicatore

An instrument to measure weak intensity of current, whose sensibility comes from the number of windings of the conducting wire around the needle.
Bussola differenziale del Siemens

Multiplier galvanometer with mobile equipment which allows to measure up the difference between the intensity of two currents; that is the reason why it is called differential galvanometer.
Galvanometro per dimostrazione

The instrument is used as an ampere meter to measure the power of current from 0 to 2 mA and from 0 to 10 A., as a voltmeter for the difference of power from 0 to 200 mvolts and from 0 to 50 volts. The physicians Deprez and D’Arsonval invented the first model of mobile coil galvanometer in 1886.
Inclinometro e declinometro

The instrument allows to measure both variation and dip of a stated place.
Interruttore di Wehnelt a una punta per corrente alternata

The device is an electrolytic switch used to obtain fast interruptions of current; in particular it improves the efficiency of Ruhmkorff spark coils.
Serie di interruttori con valvole fusibili

These devices are unipolar, bipolar and tripolar switches; basically they consist of a base on which some levers operated by means of an insulating handle are fixed.
Lampada ad arco piccola

A coal arc lamp invented by the English scientist Humphrey Davy (1778 –1829) who, in 1803, using a battery of 2000 elements, called it voltaic arc, in honour of A. Volta.
Arco voltaico

A voltaic arc characterized by a hand regulator to vary the distance of the coals. The device was united to the projectors.
Lampada a mercurio

A mercury fumes lamp; an early version is due to Arons, who, in 1882, built a model intended to be suitable for the needs of practical lighting; the model was later modified by the American Cooper-Hewitt in 1904.
Lampade ad incandescenza a filamento metallico

Metallic filament, coal filament and inert gas lamps constitute the main typologies of incandescent lamps.
Lampada Edison

The Edison lamp allows us to verify the thermo-electronic effect, discovered by the American inventor T. A. Edison (1847-1931).
Lastra di rame e zinco

The slab is made up by two metal plates, a copper one and a zinc one, joined together. It can be used to verify the Volta effect.
Macchina elettrostatica di Winter

A rubbing electric generator of the most complex kind, invented by professor Winter, from Vienna, around 1865 as bought by this school as soon as 1866.
Macchina di Holtz

Electrostatic machine, built by Holtz in 1865, used to transform mechanical energy into electric energy.
Macchine di Winshurt

Invented in 1880 by the English engineer James Wimshurt (1832-1903), the machine is one of the most developed induction electrostatic machines. Since it can produce high potential differences, it has been used for several and important applications, for example in the excitation of X-rays tubes.
Macchina magneto-elettrica del Clarke

A patented, improved, magneto-electric machine, for nervous diseases. It can treat toothache, painful tics and neuralgia. 1862, first prize medal, London 1878, silver medal, Paris
Magazzino magnetico di due lamine in cassetta

The magnetic store is made of a light wood case with a sliding cover and contains two magnetic bars of different length.
Magnete naturale armato

The device is a natural magnet whose polar expansions are equipped with an iron sheet that makes the magnetic action more effective.
Modello anello Pacinotti su sostegno

The device is a slip-ring rotor, invented by the Italian Antonio Pacinotti in 1860; making it rotate between the polar expansions of a magnet, it is possible to produce one-direction, almost constant electromotive forces, similar to the ones given by batteries and accumulators.
Modello di indotto a gabbia di scoiattolo

The “squirrel-cage” model is an example of rotor used in an asynchronous engine or “rotating field” engine. Asynchronous multiphase engines were invented by Galileo Ferraris (1847–1897) and built by Tesla. They were largely used in industry towards the end of 1800.
Modello di indotto a tamburo

A model of drum rotor for electrical engines, structured like the model of “squirrel-cage” rotor. The model of drum rotor represents one of the two main parts making up an alternating current engine; it was built only after the great discovery of the rotating magnetic field, made by Galileo Ferraris in 1885.
Modello di indotto per motore a trifase

A model of rotor for an electric triphase engine.
Modello di indotto per motore a scoppio trifase

A model similar to the preceding one; the only difference is the winding up, which is made of three sections of different colours.
Modello di indotto antico o indotto a “tamburro”

The drum rotor was invented by Pacinotti himself in 1874, and later used by the Firm Siemens.
Motore elettrico con pompa

The device is a model of electromagnetic pump used to spill liquid into a basin.
Mulinello o arganetto elettrico

The device enables to observe the dispersing power of metal points. An important use of this instrument is the pole lighting conductor invented by Franklin.
Oscillatore A.F. completo

A valve radio-receiving set whose functioning is based on the characteristic property of an oscillating circuit.
Circuito RLC

RLC circuit in series with a condenser like the one in the A.F. complete oscillator.
Pendolino elettrico

A simple device that allows to establish if a body is electrified and to determine the sign of its charges; its behaviour and use are similar to the one peculiar of an electroscope.
Pendolo di Waltenhofen

The pendulum of A.K.Waltenhofen (1828 – 1914) is used to demonstrate the breaking action due to the eddy currents, which also find a useful application in induction ovens.
Pila di Volta

The appliance is a voltaic pile defined as “column pile” because of its shape. It was built by A. Volta towards the end of 1799.
Elementi Grenet

Kind of dichromate batteries that can produce strong potential differences; they were quickly dismissed at the end of the 19th century because they supplied currents only for short periods of time. Poggendorf invented the device and Grenet followed its concrete building in 1856.
Cella elettrolitica con accessori

Volta invented this appliance, called dry battery, to try to solve some problems due to the column battery.
Pila Daniell

The English physician Daniell (1790 –1845) in 1836 improved Becquerel’s idea of a two liquids battery, obtaining a new one that was called constant current battery. This kind of battery is excellent in the operations of electro-plating, and is used in telegraphic systems.
Pile Venezia

A series of batteries of the Leclanché type. This kind of battery was produced for the first time in 1867 by the engineer J.Leclanché (1839-1882) and is the forerunner of the dry battery.
Pila termoelettrica

This battery, whose functioning is based on Seebeck effect, is used in the scientific field to explore the energy of the spectrum or to measure temperatures also as high as 1000°C, which are found in blast furnaces.
Pila termoelettrica del M. Melloni

An appliance made by bimetallic couples that can transform thermic energy. M. Melloni (1798 - 1854) built the prototype of this battery to study the thermic radiation while trying to discover analogies in the conduct of light and heat.
Coppia termoelettrica bismuto-antimonio Coppia termoelettrica rame-ferro

Thermocouples used to produce, under the Seebeck effect, a weak current which is pointed out through a galvanometer. Between the two thermocouples, when the thermic difference in level is the same, the bismuth- antimony one shows the greatest electromotive force.
Ponte di Wheatstone

Wheatstone’s bridge is used to measure an unknown resistance when we know the other three.
Pozzo di Beccaria (a)

An appliance which is used to show that in a conductor, isolated and in electrostatic equilibrium, the charges are spread on its external surface.
Pozzo di Beccaria (b)

The appliance is a Beccaria's pit.
Reostato a liquido

The appliance consists of a variable resistance and represents an alternative to wire rheostats. One kind of liquid rheostat was invented by Kundt towards the end of the 19th century.
Reostato di Poggendorff o di Wheatstone

The rheostat has the function of varying the resistance of a circuit and consequently the intensity of the power running through it. This rheostat in particular, because of its structure, allows a continuous variation of intensity.
Resistenza a corsoio montata

An example of rheostat used in electrical circuits as a variable resistance. It works as a regulator of the intensity of current or as a potentiometer, that is as a regulator of tension, when resistance and generator are in parallel.
Rettangolo Seebeck con sistema astatico

Rectangular profile device which, because of a thermo-electric effect, allows to obtain a difference in potential between the joints of the bimetallic plate that makes it up. As a consequence a current is obtained which, in its turn, generates a magnetic field. The phenomenon was discovered by Seebeck in 1823.
Rocchetto di Ruhmkorff

A device, whose functioning is based on the principle of induction. This reel was built by the German physician Ruhmkorff (Hannover 1803 - Paris 1877). The use of reels has been very important in the study of the discharge of aeriform substances and to obtain cathode and X rays.
Rocchetto a induzione

A device that transforms a direct current, produced at a low tension, into a high tension throbbing current; it is used to show the phenomenon of electromagnetic induction, the principle of the transformer and the effect of iron on magnetic circuits.
Rocchetto ad induzione su tavoletta di noce

Induction reel in which we can see the secondary winding up, two connectors with electrical connections all fixed on a strong and elegant wooden tablet.
Scampanio elettrico

If charged with an electrostatic machine, the device produces a pealing due to the collisions of a pendulum, charged for induction, which swings between the side bells and the central one. The invention of the “electric pealing” is attributed to the Benedictine Gordon (1712-1751).
Condensatore cantante del Varley

Varley’s singing condenser can be considered as a model of telephone prior to Bell’s.
Serie di ricevitori e trasmettitori telefonici

Examples of telephone receivers and transmitters and their evolution in the history of telephony.
Ricevitore telegrafico Morse

The receiver of a telegraphic system. The first electrical instruments for the telegraph were invented in 1837 by the American S.F.D. Morse (1791–1872) and, apart from him, by the British physician C. Wheatstone, in cooperation with the engineer W.F. Cooke, even if their works were based on different principles. The Morse apparatus was used in 1844 to send the first public telegram.
Relais di grande resistenza

The device can strengthen the current coming from an electric line; it was particularly used in the telegraph offices and stations, to improve the signals. This was the reason why it was also called “helper”. The invention of the electromagnetic relais is due to J Henry, who also contributed to the invention of the Morse telegraph.
Pezzo di cavo sottomarino

A sample of cable used for the underwater telegraphic lines.
Serie di valvole

Series of valves consisted of two diodes, a double diode and a thermionic rectifier. One of Marconi’s most ingenious assistants, the English A. Fleming, was the first to employ the diode to rectify an alternating current in 1904.
Solenoide con tubo di vetro ghiere e morsetti, destrorso e sinistrorso

The solenoids were used to magnetize a steel bar by induction, thus avoiding directly winding the bar with an insulating wire. When the current flows through the wire the pole can be distinguished according to the right hand rule.
Spinterometro semplice

The device allows to state the explosive distance, that is the maximum length of the electric discharge between the two circular conductors it is provided with, depending on the potential difference it is possible to establish between the spheres themselves.
Spinterometro in cassetta

This device allows the study of the phenomena concerning gas discharge in standard pressure by means of the analysis of the “disruptive spark”.
Trasformatore ad alta tensione, sistema Elster-Geitel

The apparatus is a Tesla transformer; it is used to obtain using high frequency high voltages.
Rocchetto secondario di ricambio per trasformatore, sistema Elster-Geitel
Tubi a scarica

The devices, which contain gas with a different level of rarefaction, allow to point out how the aspect of the discharge, among the electrodes they are provided with, varies depending on the pressure of the rarefied gas.
Tubo a croce o a raggi catodici

The machine allows to show the rectilinear propagation of cathode rays. The analysis of phenomena connected with the behaviour of cathode rays gave origin to studies on the nature of the atom.
Tubo di Crookes con mulinello

This kind of Crookes pipe points out the fact that the cathodic rays have a mechanic effect.
Tubo di Crookes con materia fosforescente

The pipe allows to show the capacity of cathodic rays to stimulate the fluorescence of mineral salts.
Tubi di Crookes

Other examples of Crookes’ tubes, one with globe and metallic band on the outside ampoule.
Tubo a scarica di Braun

Braun’s pipe can be considered an incandescent cathode oscillograph. The appliance allows to discover the presence of negative charges on the small particles that make up the cathode rays.
Tubi elettronici

A series of three electronic pipes of the Plucker type, one with neon, one with argon and one with mercury. J.Plücker (1801–1868), with the pipes he invented, studied the spectrum of gas substances in 1859.
Tubi Röntgen per scintille a 20 cm

In 1895 professor W.K. Röntgen (1845 –1923), at Wûrzburg university, discovered a new kind of radiation which he called X-rays while he was experimenting with the Crookes pipes.
Criptoscopio

The meaning of the word cryptoscope is: “an instruments that observes hidden things”; it was invented by professor Salvioni in 1896 and later on used in the scientific study of phenomena, for instance in the medical-surgical field. Since X-rays easily pass through the flesh and in a more difficult way through the bones, with that instrument it was possible to see on the screen, placed at the bottom of the instrument itself, the shadow of the bones of that part of the human body which was exposed to the rays.
Tubo scintillante

The device, if connected with an electrostatic machine, produces a series of sparks between the interruptions of the metallic leaves it id provided with, giving origin to bright luminous stripes, particularly effective if seen in the darkness.
Tubo di vetro armato con gancio in ottone

Another example of sparkling pipe.
Uovo elettrico

This instrument, invented by Arthur Auguste De La Rive around the second half of the 19th century, allows to observe the characteristics of a discharge at different pressure conditions.
Voltmetro e Amperometro

Fixed reel voltmeter and ampere meter.
Voltmetro con scala 250 volts

A model of voltmeter with bakelite case, mounted on a wooden base.
Voltmetro con scala 0-15 volts

Voltmeter with bakelite case. The device is equipped with a non-linear scale, 0-15 volts.
Voltmetro SVIME 150 volts

Sample of voltmeter. This device is equipped with a non linear scale, 0-150 Volts.