Conduction: current effects


 

 

 

   

RHEOSTAT WITH RUNNER

 
 School
  Spano

  Function
  They are used to change the current intensity or as potentiometers to change the difference of potential.
Maker:
Officine Galileo - Florence
Price: L 50 Purchase date: 1931

  Description
  They are made with a bare constantan wire wound at helix on a state ruler. A copper multiple connection rests on the wire. The connection is driven by a brass pole parallel to the ruler. Terminal boards are placed at the ends of the resistance and on the driving pole of the cursor.

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RHEOSTAT WITH DOUBLE RUNNER

 
 School
  Spano

  Function
  They are used to change the current intensity or as potentiometers to change the difference of potential.
Maker:
Officine Galileo - Florence
Price: L 98 Purchase date: 1931

  Description
  The model is made with a wire wound on two slate prisms supported by the same metallic frame and with two different cursors. The disposition of the terminal boards is such that the two resistances can have connections parallel or in series, allowing a larger use of the apparatus. A data plate applied to the cursor of every rheostat indicates the total resistance and the current in amperes that the rheostat can sustain for a short time without danger. Fifty per cent of the current indicated can be sustained without a great increase of the temperature.

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VARIABLE RESISTANCE

 
 School
  University

  Function
  Variable resistance to be inserted in the circuit.
Maker: Unsigned Price: Purchase date:

  Description
  It is a rheostat with a carbon resistance. By rotating the carbon cylinder we change the position where the contact happens between the little metallic wheel and the lateral surface of the cylinder.
  The surfaces of the basis of the cylinder are each connected to a chuck. The wheel is connected to a third chuck.

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RHEOCORD

 
 School
  University

  Function
  To measure resistances.
Maker: Unsigned Price: Purchase date: 1922

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SERIES RESISTANCE BOX

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

  Function
  To have resistances of different quantities.
Maker:
(1) Unsigned
(2) Officine Galileo - Florence  
Price:
-
L 250
  Purchase date:
-
1931

  Description
  It is formed by a shining wooden case, plug-connections, doubly wound manganin resistances protected by an insulating varnish.
  Precision 1% for the resistance from 10000 to 100ohm, 0.2% from 10 to 1 ohm; 0.5% for those of 0.1 ohm.

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SHUNT

 
 School
  Spano

  Function
  To change the range of the galvanometers.
Maker:
Officine Galileo - Florence
Price: L 400 Purchase date: 1931

  Description
  It is made of a cylindrical brass case with an ebonite lid. The ends of the resistances in the case terminate with brass blocks and are inserted in parallel on the galvanometer circuit with plugs.

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WHEATSTONE BRIDGE

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

  Function
  To measure resistances.
Maker:
(1) Officine Galileo - Florence
(2) Phywe
Price:
L 370
-
Purchase date:
1931
-

  Description
  A calibrated silver nickel wire is stretched on a 1.20 m mahogany basis that lies on a one-meter millimetric scale. A cursor slides on the wire. Two copper wires applied under complete the rectangle and are collected to the terminal boards of the unknown resistance, of the calibrated resistance and of the cell. The circuits are indicated with very visible white lines.

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RESISTANCES WITH FOUR LAMPS IN SERIES OR IN PARALLEL

 
 School
  Spano

  Function
  To study the resistances.
Maker:
Officine Galileo - Florence
Price: L 180 Purchase date: 1931

  Description
  Four lamp-holders are mounted on the same table with extreme and intermediate binding posts and with a general switch. In this way the lamps can be connected in series and in parallel.

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STANDARD RESISTANCE OF SIEMENS


  Function
  To measure resistances.
Maker: Unsigned Price: L 15 Purchase date: 1882

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TEST STAND

 
 School
  Spano

  Function
  To study the electric current.
Maker:
Made in the school
Price: L 6 Purchase date: 1933

  Description
  On a rectangular table there are: a lamp-hold with a lamp, an outlet, a switch, a bell and two binding posts.

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SMALL HAND FEED ARC LAMP

 
 School
  Spano

  Function
  It is used as a light source in various experiments.
Maker:
Officine Galileo - Florence
Price: L 180 Purchase date: 1931

  Description
  The supports of the two carbons are mounted on a glass column. The top carbon moves vertically. The ensemble is mounted on a cast iron tripod. We can use carbons with a diameter up to six millimetres.

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COOKER

 
 School
  University

  Function
  To show the transformation of the electric energy into heat.
Maker: Unsigned Price: Purchase date:

  Description
  From a wooden rectangular basis rise two little columns. From these two little bars branch off horizontally, one of which supports a carbon electrode while the other supports a little cup.
  It is an arc-lamp in which one of the carbons has been substituted by the melting-pot.

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KOHLRAUSH'S CELL

 
 School
  University

  Function
  To measure the resistance of an electrolyte.
Maker: Unsigned Price: 12.5 Purchase date:

  Description
  It is formed by a glass container placed on a wooden basis. The electrodes are formed by pierced metallic disks. A central hole on the lid is used to insert the thermometer that also goes through the holes of the disk.

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VOLTAMETER

 
 School
 University

  Function
 To show the chemical effects of the electric current.
Maker: Unsigned Price: Purchase date: Cat 1882

  Description
  It is formed by a V-shaped glass tube grafted vertically on a low column that leans on a wooden circular basis. The electrodes are placed at the end of the tube.

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BERTRAM'S VOLTAMETER

 
 School
  University (1),   Azuni (2)
(1)

  Function
  To show the chemical effects of the electric current.
Maker: Unsigned Price: L 12.5 Purchase date: 1912

  Description
  To obtain the electrolysis with this voltameter we pour acidulous water into the tank and then we fill the two little bells with the same liquid. Then, keeping them closed with a finger, we overturn them and we immerse them into the liquid of the tank by hanging them to their respective hooks. Then we connect the electrodes to a 4-6 volt cell.

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APPARATUS FOR ILLUSTRATING JOULE’S EFFECT

 
 School
  Spano

  Function
  To show the transformation of the electric energy into heat.
Maker:
Officine Galileo - Florence
Price: L 250 Purchase date: 1931

  Description
  Two spirals of niccolite, one with a resistance twice as the other, are stretched on the two balloons, each one of which communicating with a tube. After opening the upper keys, we pour a coloured liquid into the manometer, and then we close the keys. We send the current into the two spirals connected in series and we observe a different shift in the two manometers. The middle binding post allows using the two spirals separately to demonstrate that the quantity of developed heat is directly proportional to the square of the current intensity for the same conductor.
  For the two experiences a tension of 4 volt is enough, with a rheostat in series to regulate the current intensity.

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