Vacuum tubes


 

 

 

 

 

 

   

PHOTOCELL

 
 School
  Spano

  Function
  To study the photoelectric effect, i.e. the capacity of the light to supply enough energy to extract electrons from certain substances.
Maker:
Officine Galileo - Florence
Price: L 350 Purchase date: 1932

  Description
  It is made of a steel plate that supports a thin layer of a compound of suitably worked selenium. On these layers a thin transparent metallic film is placed.

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VACUUM SCALE

 
 School
  University

  Function
  To show the electric charge in very rarefied air.
Maker:
Max Kohl - Chemnitz
Price:
£ 51
Purchase date:
1908

  Description
  Six tubes, with different pressures inside, are mounted on the same panel placed vertically on an wooden basis. The tubes are held a the bottom by a metallic strip with a binding post placed on the basis, at the top they are held by single metallic plates anchored to the panel.

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GEISSLER TUBES

 
 School
  Spano (1),   Castelvž (2)

  Function
  To show the electric charge in very rarefied air.
Maker:
(1) Officine Galileo - Florence
(2) Unsigned
Price:
L 220
L 5 * 2
Purchase date:
1936
1905

  Description
  They are made on fluorescent glace and hold very rarefied air. These tubes of different shapes and sizes are provided with ring joints with aluminium electrodes.

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CROOKES'S TUBES WITH THREE ANODES

 
 School
  University (1),   Spano(2)

  Function
  To study the electric discharges in a low and in a very low pressure environment.
Maker:
(1) Unsigned
(2) Officine Galileo - Florence
Price:
L 50
L 50
Purchase date:
1923
1931

  Description
  Both have a spherical form with four electrodes and a shining wooden foot.
  With the first apparatus we can verify that the discharge happens following the shortest way between the two points of the current connection.
  With the second apparatus we can verify that the beam of cathode rays always follows the same direction whatever the anode connection.

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CYLINDRICAL TUBE

 
 School
  Spano

  Function
  To show the mechanical action of the cathode rays.
Maker:
Officine Galileo - Florence
Price: L 115 Purchase date: 1931

  Description
  It contains a light whirl sliding on glass guides. When it is struck by the cathode rays the whirl moves.

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VACUUM TUBE WITH A SCREEN AND A SLIT

 
 School
  Pellegrini

  Function
  To show the electric conduction in rarefied gases.
Maker: Unsigned Price: Purchase date:

  Description
  The beam of the cathode rays comes into the central side of the tube through a slit. It is made visible by an oblique fluorescent screen when iy goes near it.

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BRAUNíS TUBE

 
 School
  University

  Function
  To study the action of the magnetic fields on the cathode rays.
Maker: Unsigned Price: Purchase date:

  Description
  It contains a cathode at the thinner end, a metallic diaphragm with a central circular opening, and a thin mica layer covered with a fluorescent substance at the wider end. When it works, the beam of cathode rays that crosses the diaphragm, provokes the fluorescence on a small part of the mica disk, aligned with the cathode and the diaphragm hole. This demonstrates that the cathode rays go in a straight line from the cathode to the screen. If we approach a magnet between the diaphragm and the screen, the fluorescent spot moves. This demonstrates that the cathode rays are deviated by a magnetic field, and they behave as negative charged particles with great speed.

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BRAUN-WEHNELTíS TUBE

 
 School
  University

  Function
  To study the action of the cathode rays in the electric and magnetic fields.
Maker: Unsigned Price: L 450 Purchase date: 1923

  Description
  It is similar to Braunís tube, but it has also a capacitor with parallel plates. If we can set an electric field between the armatures, the spot on the screen moves from its initial position. The electrons deviate towards the plate with the highest potential.
  The tube can serve to determinate the speed of the cathode rays and the ration between an electron charge and its mass.

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VACUUM TUBE

 
 School
  University

  Function
  To show the electric conduction in rarefied gases.
Maker: Unsigned Price: Purchase date:

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DISCHARGE TUBE

 
 School
  University

  Function
  To show the electric conduction in rarefied gases.
Maker: Unsigned Price: Purchase date:

  Description
  The tube shows three branches in the central part. The electrodes are placed on two of these, while the third is used to link it to a pneumatic pump.

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DISCHARGE TUBE

 
 School
  University

  Function
  To show the electric conduction in rarefied gases.
Maker: Unsigned Price: Purchase date:

  Description
  It is formed by a glass tube, with two electrodes at the ends. The vacuum is obtained by linking the tube to a pneumatic pump.

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TUBE WITH CROSS

 
 School
  University (1),   Spano (2)
(1)

  Function
  To show the rectilinear motion of the electrons.
Maker: Unsigned Price: Purchase date: 1923

  Description
  Along the trajectory of the electrons of a divergent beam we place an obstacle with the form of a Malta cross whose shadow we can see on the fluorescent screen.

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RŒNGTEN TUBE

 
 School
  University (1),   Spano (2)
(1)

  Function
  To show that the bodies are transparent to x-rays.
Maker: Unsigned Price: L 253.2 Purchase date: 1913

  Description
  The x-rays produced by this tube have a great penetration power and show clearly a hand and the wrist bones or the coin contained in a bag.

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THERMOIONIC TUBE

 
 School
  Spano

  Function
  Used in different electronics applications.
Maker: Unsigned Price: Purchase date:

  Description
  Electronic tube with a hot cathode with emission of electrons due to the thermionic effect. The control of the electron movement is made with the control electrode and the anode.

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CRYSTAL RECTIFIER

 
 School
  Spano

  Function
  Rectifier for low tension currents.
Maker: Unsigned Price: L 4.5 Purchase date:

  Description
  It is made of a little spring, and of which is placed in contact with a crystal of galena (PbS). The other end of the spring and the galena are connected to the electrodes of a plug that can be inserted in a circuit.

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CRYPTOSCOPE

 
 School
  University (1),   Spano (2)

  Function
  To individuate the bodies crossed by x-rays.
  Maker:  
(1) Unsigned
(2) Officine Galileo - Florence  
    Price:  
L 76.5
L 120
    Purchase date:
Cat. 1882
1931

  Description
  It is formed by a fluorescent screen placed on a pyramidal case with handle.

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RADIUM SALT

 
 School
  Spano

  Function
  To show the emission of charged particles by radioactive substances.
Maker:
Officine Galileo - Florence
Price: L 220 Purchase date: 1936

  Description
  The salt is applied to the internal wall of a little glass bulb, that is protected by a metallic cage and closed in a massive brass case.
  If we draw the salt near an electroscope the leaves close whatever their divergence.

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