1 / 70

Measuring the strength of a Magnetic Field

Measuring the strength of a Magnetic Field. © David Hoult 2009. When current flows through a conductor which is in a magnetic field, it experiences a force, except when the conductor is. © David Hoult 2009.

orsin
Download Presentation

Measuring the strength of a Magnetic Field

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Measuring the strength of a Magnetic Field © David Hoult 2009

  2. When current flows through a conductor which is in a magnetic field, it experiences a force, except when the conductor is © David Hoult 2009

  3. When current flows through a conductor which is in a magnetic field, it experiences a force, except when the conductor is parallel to the flux lines © David Hoult 2009

  4. When current flows through a conductor which is in a magnetic field, it experiences a force, except when the conductor is parallel to the flux lines The direction of the force is at 90° to both the current and the flux lines © David Hoult 2009

  5. When current flows through a conductor which is in a magnetic field, it experiences a force, except when the conductor is parallel to the flux lines The direction of the force is at 90° to both the current and the flux lines Fleming’s left hand rule helps to remember the relation between the three directions… © David Hoult 2009

  6. © David Hoult 2009

  7. © David Hoult 2009

  8. Thumb First finger Second finger © David Hoult 2009

  9. ThuMb Motion First finger Second finger © David Hoult 2009

  10. ThuMb Motion First finger Field Second finger © David Hoult 2009

  11. ThuMb Motion First finger Field SeCond finger Current © David Hoult 2009

  12. © David Hoult 2009

  13. © David Hoult 2009

  14. © David Hoult 2009

  15. © David Hoult 2009

  16. Factors affecting the Magnitude of the Force The force depends on © David Hoult 2009

  17. The force depends on - the current flowing through the conductor, I © David Hoult 2009

  18. The force depends on - the current flowing through the conductor - the length of conductor in the field © David Hoult 2009

  19. The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that © David Hoult 2009

  20. The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F acurrent, I © David Hoult 2009

  21. The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F acurrent, I F alength of conductor, L © David Hoult 2009

  22. The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F a current, I F a length of conductor, L F = I L × a constant © David Hoult 2009

  23. The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F a current, I F a length of conductor, L F = I L × a constant magnetic field strength or © David Hoult 2009

  24. The force depends on - the current flowing through the conductor - the length of conductor in the field Experiments show that F a current, I F a length of conductor, L F = I L × a constant magnetic field strength or magnetic flux density © David Hoult 2009

  25. F = ILB © David Hoult 2009

  26. F = ILB units of B Newtons per Amp per meter, NA-1m-1 © David Hoult 2009

  27. F = ILB units of B Newtons per Amp per meter, NA-1m-1 1NA-1m-1is called 1 Tesla (1T) © David Hoult 2009

  28. F = ILB units of B Newtons per Amp per meter NA-1m-1 1NA-1m-1 is called 1 Tesla (1T) The flux density of a magnetic field is © David Hoult 2009

  29. F = ILB units of B Newtons per Amp per meter NA-1m-1 1NA-1m-1 is called 1 Tesla (1T) The flux density of a magnetic field is the force per unit current per unit length acting on a conductor placed at 90° to the field © David Hoult 2009

  30. F = ILB units of B Newtons per Amp per meter NA-1m-1 1NA-1m-1 is called 1 Tesla (1T) The flux density of a magnetic field is the force per unit current per unit length acting on a conductor placed at 90° to the field F = ILBsinq © David Hoult 2009

  31. Force acting on a charged particle moving through a magnetic field © David Hoult 2009

  32. © David Hoult 2009

  33. Consider a conductor of length L, having n free electrons per unit volume. A current, I, is flowing through it © David Hoult 2009

  34. Consider a conductor of length L, having n free electrons per unit volume. A current, I, is flowing through it © David Hoult 2009

  35. In this piece of conductor there are © David Hoult 2009

  36. In this piece of conductor there are NAL free electrons © David Hoult 2009

  37. In this piece of conductor there are NAL free electrons If all these electrons pass through end x in time t then the current, I is given by © David Hoult 2009

  38. In this piece of conductor there are NAL free electrons If all these electrons pass through end x in time t then the current, I is given by nALe t © David Hoult 2009

  39. If there is a magnetic field of flux density B at 90° to the current, the conductor will experience a force of magnitude © David Hoult 2009

  40. If there is a magnetic field of flux density B at 90° to the current, the conductor will experience a force of magnitude ILB © David Hoult 2009

  41. If there is a magnetic field of flux density B at 90° to the current, the conductor will experience a force of magnitude ILB This is the sum of the forces on all the electrons, so the force F acting on each electron is given by © David Hoult 2009

  42. If there is a magnetic field of flux density B at 90° to the current, the conductor will experience a force of magnitude ILB This is the sum of the forces on all the electrons, so the force F acting on each electron is given by ILB IB F = = nA nAL © David Hoult 2009

  43. Substituting for I gives F = © David Hoult 2009

  44. Substituting for I gives nALeB F = = tnA © David Hoult 2009

  45. Substituting for I gives nALeB LeB F = = tnA t © David Hoult 2009

  46. Substituting for I gives nALeB LeB F = = tnA t © David Hoult 2009

  47. but L/t is © David Hoult 2009

  48. but L/t is the (drift) velocity of the electrons © David Hoult 2009

  49. but L/t is the (drift) velocity of the electrons therefore © David Hoult 2009

  50. but L/t is the (drift) velocity of the electrons therefore F = e v B © David Hoult 2009

More Related