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Magnetic field lines

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Magnetic field lines

  1. 1. Magnetic Field Sources
  2. 2. Magnetic Fields <ul><li>A force field that denotes the area in which the non-contact force of permanent magnets or current carrying conductors can exert their influence </li></ul><ul><li>Fields are concentrated at the poles </li></ul><ul><li>Same properties with Electric field lines except that there is no magnetic monopole </li></ul>
  3. 3. Magnetic field lines
  4. 4. Magnetic Force <ul><li>Like poles repel, opposite attract </li></ul><ul><li>An object that contains iron but is not itself magnetized is attracted by either pole of a permanent magnet. </li></ul>
  5. 5. Magnetic Force
  6. 6. Magnetic interactions can be described as: <ul><li>A moving charge or a current creates a magnetic field in the surrounding space (in addition to its electric field) </li></ul><ul><li>The magnetic field exerts a force F m on any other moving charge or current that is present in the field. </li></ul><ul><li>The magnetic force F m acting on a positive charge q moving with velocity v is perpendicular to both F m and the magnetic field B. </li></ul>
  7. 7. Units of Magnetic Fields <ul><li>SI units: tesla , T </li></ul><ul><li>1 tesla = 1 T = 1 N/A · m </li></ul><ul><li>Or: gauss , G </li></ul><ul><li>1 G = 10 -4 T </li></ul>
  8. 8. Magnetic Force on Moving Charge <ul><li>Moving charged particles are deflected in magnetic fields </li></ul><ul><li>Right-Hand Rule </li></ul>
  9. 9. Grip and Hand Rules Out of the Page In to the Page
  10. 11. Magnetic Force on Moving Charge The magnetic force is always perpendicular to v ; a particle moving under the action of a magnetic field alone moves with a constant speed.
  11. 12. Motion of charged particles in a magnetic field
  12. 13. Motion of charged particles in a magnetic field Fig. 27.18
  13. 14. Motion of charged particles in a magnetic field Fig. 27.17
  14. 15. Applications of motion of charged particles <ul><li>Velocity Selector </li></ul><ul><li>Particles of a specific speed can be selected from the beam using an arrangement of electric and magnetic fields called a velocity selector. </li></ul>
  15. 16. Magnetic Force on Current Carrying Wire
  16. 17. Magnetic Force on Current Carrying Wire
  17. 18. Ampere’s Law <ul><li>Used to determine the magnetic field yielded by current-carrying wire </li></ul><ul><li>Ampere’s law states that the product B and length of line segment around any closed path equals µ 0 times the net current through the area enclosed by the path. </li></ul><ul><li>Direction of Magnetic field is determined by corkscrew method </li></ul>
  18. 19. Ampere’s Law B=  0 I/2  L
  19. 20. Magnetic field profile of 2 parallel current carrying wires
  20. 21. Solution
  21. 22. Magnetic Field in Solenoid
  22. 23. Magnetic Field in Solenoid B=  0 nI
  23. 24. Ampere’s Experiment B 1 =  0 I 1 /2  L F=  0 I 1 I 2 l/2  L
  24. 25. Exercise B 1 =  0 I 1 /2  L F/l=  0 I 1 I 2 /2  L
  25. 26. Example <ul><li>Suspending a current with a current </li></ul><ul><li>A horizontal wire carries a current I 1 =80 A dc. A second parallel wire 20 cm below it must carry how much current I 2 so that it doesn’t fall due to gravity? The lower wire is a homogenous wire with a mass of 0.12 g per meter of length. </li></ul>F/L = mg/L =1.18 x 10 -3 N/m  0 I 1 I 2 /2  L = 1.18 x 10 -3 N/m I 2 = 15 A
  26. 27. Definitions <ul><li>Ampere current flowing in each of the two long parallel conductors 1 m apart, which results in a force of exactly 2 x 10 -7 N/m of length of each conductor. </li></ul><ul><li>Coulomb one ampere-second </li></ul>
  27. 28. Solution Set F/l=  0 I 1 I 2 /2  L F A /l= 5.83 x 10 -5 N/m; 90 F B /l=3.37 x 10 -5 N/m; -60 F C /l=3.37 x 10 -5 N/m; 240

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