FSAC 1430 Physique T4 : électricité et magnétisme
Semaine 6 : Magnétostatique (seconde partie)
APE (apprentissage par exercices)
Chaque étudiant doit préparer, en groupe ou seul, une solution pour les exercices 2, 3, 4 et 5 de la liste ci-dessous. Lors de la seconde séance de tutorat, chacun doit pouvoir présenter cette solution et pouvoir répondre aux questions posées par le tuteur en utilisant uniquement cette solution et son document de synthèse personnel (12 pages maximum à ce stade). Indication : dans le vide, on a B = mo H .
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1. Young & Freedman, ed. 10, p. 934, ex. 29.14 (or ed. 11, p.1097, ex. 28.21) Three parallel wires each carry current I in the directions shown in Fig. S06-20. If the separation between adjacent wires is d, calculate the magnitude and direction of the net magnetic force per unit length on each wire. |
Figure S06-21 |
Figure S06-22 |
2. Young & Freedman, ed. 10, p. 934, ex. 29.23 (or ed. 11, p.1098, ex. 28.31) + ... Figure S06-22 shows, in cross section, several conductors that carry currents through the
plane of the figure. The currents have the magnitudes I1 = 4.0 A,
I2 = 6.0 A and I3 = 2.0 A, and the directions shown. Four paths,
labeled a through d, are shown. What are the line integrals
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3. Young & Freedman, ed. 10, p. 935, ex. 29.28 (or ed. 11, p.1099, ex. 28.38) + ...
A toroidal solenoid (see ed. 10, p. 921, Fig. 29-21 or ed. 11, p 1085, Fig. 28.23) has inner radius r1 = 15.0 cm and outer radius r2 18.0 cm. The solenoid has 250 turns and carries a current of 8.50 A. What is the magnitude of the magnetic fields H and B at the following distances from the center of the torus:
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Figure S06-24 |
4. Young & Freedman, ed. 10, p. 937, ex. 29.52 (or ed. 11, p.1101, ex. 28.64) + ... The wire semicircles showed in Fig. S06-24 have radii a and b. Calculate the net magnetic fields H and B (magnitude and direction) that the current in the wires produces at point P. |
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5. Young & Freedman, ed. 10, p. 935, ex. 29.24 + p. 938, ex. 29.58 (or ed. 11, p. 1099; ex. 28.32 + p.1102, ex. 28.70 ) + … A solid conductor with radius a is supported by insulating disks on the axis of a conductor tube with inner radius b and outer radius c (see Fig. S06-25). The central conductor and tube carry equal currents I in opposite directions. The currents are distributed uniformly over the cross sections of each conductor.
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Figure S06-25 |
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Figure S06-26 |
6. Young & Freedman, ed. 10, p. 939, ex. 29.65 (or ed. 11, p.1103, ex. 28.79) + ... Long, straight conductors with square cross sections and each carrying current I are laid side-by-side to form an infinite current sheet (see Fig. S06-26). The conductors lie in the xy-plane, are parallel to the y-axis and carry current in the + y-direction. There are n conductors per unit length measured along the x-axis.
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7. Young & Freedman, ed. 10, p. 940, ex. 29.73 (or ed. 11, p.1104, ex. 28.85) + …
A thin disk of dielectric material with radius a has a total charge +Q distributed uniformly over its surface. It rotates n times per second about an axis perpendicular to the surface of the disk and passing through its center. Find the magnetic field at the center of the disk. (Hint: Divide the disk into concentric rings of infinitesimal width.)
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Dernière mise à jour le 21-10-2004
and 
for each path? Each integral involves going
around the path in the counterclockwise direction. Which are the results that remain valid even if the wires cross magnetic materials, but the integration paths don't cross those materials? Which are the results that remain valid even if the integration paths cross magnetic materials? Explain yours answers.
