Matteucci surprising discoveries about Magnetism

[hanon]

Hi all,

The aim of this post is to show a very few known discoveries done by physicist Carlos Matteucci around 1850.

His experiments where collected in his book "Cours spécial sur l'induction, le magnétisme de rotation, le diamagnétisme" (Special Course on Induction, Magnetism of Rotation and Diamagnetism) (1854, Paris), and I found them into the spanish version (3rd ed. 1862) "Elementary treatise on physics experimental and applied for the use of colleges and schools" book written by Ganot. This is the machine translation of his findings:


"Having studied M. Matteucci the same phenomena , though more accurately , he recognized that are more complicated than I thought. Fig. 542 represents the physical apparatus used for this . Consists of a wooden box, in which a series of gears transmit through a crank M , a rotational movement more or less rapidly to a metal disc A of 20 centimeters in diameter. Beneath the disk, at a distance of 2 to 3 millimeters , there is a powerful electro- magnet ab , which moves in a slot so that it can submit its poles successively all points of the disc. Finally, above the disc there are two copper rods and n , each terminated by a blunt tip and amalgamated in contact with the disc. These same rods communicating , at its upper end , with the two wire ends of the galvanometer , and also because the arrangement of the supports to which are fixed , can occupy any position relative to the center and circumference of the disc .

     Now, using this apparatus, and putting one end of the wire galvanometer contact the center , and the other with the different parts of the disk surface, M. Matteucci has demonstrated the following facts , shown in FIG . 543, in which the points N and S are the projections of the two poles of the electro - magnet, and the straight line AB on these two poles:

     1º M. Matteucci found zero current lines , a, b , c, d, e , which are normal to the line AB, and are contoured near the edges of the disc , so that they cut iy  perpendicularly.

     2º The projection of each pole of the electro - magnet on the disc is a neutral point , ie zero current , plus a neutral line rr , substantially circular , which passes through the projections of the two poles , and is center the axis of electro- magnet, is simultaneously inversion line , ie the currents inside and outside of these lines are of opposite direction.

     3º Electrical currents lines , ie those which are performed by the maximum of effect , usually always cut zero current lines and are tangent to the line AB , the maximum current lines are represented in m, n , p , q, in the previous figure.

     4º Position of neutral lines , rS, rN , which passes through the projections of the two poles is not appreciably changed by the nature of the disc, or by its thickness or the intensity of the current of the battery, but this line is folded back on itself as the rotation speed increases.

     5º Finally, each side of the neutral points on the polar diameter are two maximum points which distance depends on the thickness of the electro- magnet, and the diameter of the rotating disk.

     For more details about these curious phenomena , become the reader's attention on the special course at induction and magnetism of rotation, published in late 1854 by M. Matteucci .
"

Link: http://www.cervantesvirtual.com/obra-visor/tratado-elemental-de-fisica-experimental-y-aplicada-y-de-meteorologia-con-numerosa-coleccion-de-problemas--0/html/fefd756e-82b1-11df-acc7-002185ce6064_11.htm

[ariovaldo]

Hi all,

The aim of this post is to show a very few known discoveries done by physicist Carlos Matteucci around 1850.

His experiments where collected in his book "Cours spécial sur l'induction, le magnétisme de rotation, le diamagnétisme" (Special Course on Induction, Magnetism of Rotation and Diamagnetism) (1854, Paris), and I found them into the spanish version (3rd ed. 1862) "Elementary treatise on physics experimental and applied for the use of colleges and schools" book written by Ganot. This is the machine translation of his findings:


"Having studied M. Matteucci the same phenomena , though more accurately , he recognized that are more complicated than I thought. Fig. 542 represents the physical apparatus used for this . Consists of a wooden box, in which a series of gears transmit through a crank M , a rotational movement more or less rapidly to a metal disc A of 20 centimeters in diameter. Beneath the disk, at a distance of 2 to 3 millimeters , there is a powerful electro- magnet ab , which moves in a slot so that it can submit its poles successively all points of the disc. Finally, above the disc there are two copper rods and n , each terminated by a blunt tip and amalgamated in contact with the disc. These same rods communicating , at its upper end , with the two wire ends of the galvanometer , and also because the arrangement of the supports to which are fixed , can occupy any position relative to the center and circumference of the disc .

     Now, using this apparatus, and putting one end of the wire galvanometer contact the center , and the other with the different parts of the disk surface, M. Matteucci has demonstrated the following facts , shown in FIG . 543, in which the points N and S are the projections of the two poles of the electro - magnet, and the straight line AB on these two poles:

     1º M. Matteucci found zero current lines , a, b , c, d, e , which are normal to the line AB, and are contoured near the edges of the disc , so that they cut iy  perpendicularly.

     2º The projection of each pole of the electro - magnet on the disc is a neutral point , ie zero current , plus a neutral line rr , substantially circular , which passes through the projections of the two poles , and is center the axis of electro- magnet, is simultaneously inversion line , ie the currents inside and outside of these lines are of opposite direction.

     3º Electrical currents lines , ie those which are performed by the maximum of effect , usually always cut zero current lines and are tangent to the line AB , the maximum current lines are represented in m, n , p , q, in the previous figure.

     4º Position of neutral lines , rS, rN , which passes through the projections of the two poles is not appreciably changed by the nature of the disc, or by its thickness or the intensity of the current of the battery, but this line is folded back on itself as the rotation speed increases.

     5º Finally, each side of the neutral points on the polar diameter are two maximum points which distance depends on the thickness of the electro- magnet, and the diameter of the rotating disk.

     For more details about these curious phenomena , become the reader's attention on the special course at induction and magnetism of rotation, published in late 1854 by M. Matteucci .
"

Link: http://www.cervantesvirtual.com/obra-visor/tratado-elemental-de-fisica-experimental-y-aplicada-y-de-meteorologia-con-numerosa-coleccion-de-problemas--0/html/fefd756e-82b1-11df-acc7-002185ce6064_11.htm

Interesting..