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Magnetism

Magnetism. Magnetism. Magnets have two poles that attract opposite poles and repel similar Domains are aligned Has a magnetic field Easy to detect magnetism, although it is not easy to measure its strength Make a magnet by rubbing steel against another magnet. Properties of Magnetism.

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Magnetism

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  1. Magnetism

  2. Magnetism • Magnets have two poles that attract opposite poles and repel similar • Domains are aligned • Has a magnetic field • Easy to detect magnetism, although it is not easy to measure its strength • Make a magnet by rubbing steel against another magnet

  3. Properties of Magnetism • Magnetism is a force that attracts iron, nickel and cobalt • Combinations of these metals as alloys can become permanent sources of magnetism • A lodestone is the naturally occurring magnetite that has the chemical formula Fe3O4

  4. Two Poles • Opposite ends of a magnet are called its north and south poles • should be called the "north seeking" and "south seeking" poles, because they seek the Earth's North Pole and South Pole, respectively • Like poles repel • north pole of magnet will push the north pole of another magnet

  5. What is attracted to the north end of the magnet? A) The north B) The south C) The east D) The west

  6. What do similar poles do? A. Attract B. Repel They melt They expand

  7. Magnetism • Magnets have two poles that attract opposite poles and repel similar • Domains are aligned • Has a magnetic field • Easy to detect magnetism, although it is not easy to measure its strength • Make a magnet by rubbing steel against another magnet

  8. Magnetic Field Nature • Magnetism originates in the motion of the electrons • Spinning electrons act like tiny magnets • Cancellation of this effect occurs in most materials • Iron, nickel, cobalt are exceptions

  9. Magnetic Domains • The magnetic north-south axes of groups of iron atoms line up in the same direction • Magnetic domains • Domains are randomly oriented unmagnetized iron

  10. Magnetization • An external magnetic field will twist the domains into alignment • Domains are randomly oriented in unmagnetized iron • Incomplete alignment of domains in slightly magnetized iron • Virtually all of the domains are aligned in strongly magnetized iron

  11. Make a magnet by rubbing iron against another magnet

  12. What are magnetic domains? A. Atoms randomly aligned B. Electrons flowing in an iron C. Moving electric charge D. Clusters of protons E. Clusters of aligned atoms

  13. Which of the following domain is the strongest magnet? A. Electrons spinning in opposite directions B. Electrons spinning in the same direction C. Electrons merging with protons D. Half a magnet E. Electrons not spinning

  14. How is a magnetic field produced? A. flow of electrons and neutrons B. motion of electric charge C. force exerted by the poles D. path of magnetic domains

  15. A magnet is broken into two equal pieces. What happens to each piece? A. One piece stays magnetized while the other becomes unmagnetized. B. One piece is stronger than the other C. Each piece retains equally strong poles D. One piece acquires the North Pole while the other has the South Pole.

  16. Magnetism • Magnets have two poles that attract opposite poles and repel similar • Domains are aligned • Has a magnetic field • Easy to detect magnetism, although it is not easy to measure its strength • Make a magnet by rubbing steel against another magnet

  17. Detecting Magnetic Field • Iron filings on a piece of paper • Spread fine iron filings on a piece of paper laid on top of a magnet • Outline of the magnetic lines of force or the magnetic field

  18. Detecting Magnetic Field • Compass • Thin magnet or magnetized iron needle balanced on a pivot • needle will rotate to point toward the opposite pole of a magnet • One end marked N and the other S

  19. A Compass →Magnetic Field

  20. Electric Currents and Magnetic Field3 • Magnetic field lines around a long wire which carries an electric current form concentric circles around the wire • The direction of the magnetic field is in the direction the fingers if your right hand curls around the wire with your thumb in the direction of the current

  21. Iron Filings form Concentric Circles around Wire

  22. Electric Currents and Magnetic Field

  23. Electric Currents and Magnetic Field • Spinning or rotating electrons are responsible for magnetism in iron • Moving charges set up magnetic fields • Compasses (bar magnets) line up in circles around a wire carrying current.

  24. Which of these are not used to find magnetism? A) A compass B) A wire with current C) An ammeter D) Iron fillings

  25. The direction of the field arrows outside the magnet is A. From the north to the south pole B. From the south to the north pole C. From the center to both poles

  26. Which of these are not used to find magnetism? A) A compass B) A wire with current C) An ammeter D) Iron fillings

  27. How do you detect magnetic field direction? A) A thermometer B) A compass C) A metal detector D) An ammeter

  28. What are the three elements that are magnetic? A) Iron, Nickel, and Copper B) Nickel, Zinc, and Copper C) Copper, Cobalt, Zinc D) Iron, Nickel, and Cobalt

  29. Magnetism • Magnets have two poles that attract opposite poles and repel similar • Domains are aligned • Has a magnetic field • Easy to detect magnetism, although it is not easy to measure its strength • Make a magnet by rubbing steel against another magnet

  30. Measuring Magnetic Strength • The average flux density in the Earth's outer core was calculated to be 25 Gauss. • The earth's magnetic field is 0.5 Gauss • A refrigerator magnet is 10 Gauss

  31. What is used to measure magnetism? A) Ammeter B) Compass C) Gage meter D) Gauss meter E) B and D

  32. What causes a current measuring apparatus to work? A) magic B) A device measures electrons C) Current pushes a spring D) A current makes a magnet

  33. Magnetism • Magnets have two poles that attract opposite poles and repel similar • Domains are aligned • Has a magnetic field • Easy to detect magnetism, although it is not easy to measure its strength • Make a magnet by rubbing steel against another magnet

  34. Make a magnet by rubbing iron against another magnet

  35. Make a magnet by cooling molten iron in a magnetic field

  36. Uses of Magnetism • Levitation • Forces Through a Magnetic Field • Earth Magnetic Field • The Sun

  37. Magnetic Levitation • Trains float above guide way due to magnetic field • Travel at speeds of up to 300 mph (500 kph)

  38. Railgun • Electromagnetic current is used to accelerate a nonexplosive bullet at several times the speed of sound. • Projectile zips along a set of electrically charged parallel rails and out of the barrel at speeds up to 5000 mph or Mach 7 • The result: a weapon that can hit a target 100 miles or more away within minutes. Read more: http://www.foxnews.com/scitech/2010/12/10/navy-railgun-shoots-bullets-electromagnet/#ixzz1S7fXUGB0

  39. Space Launch System There is a proposed plan that would start with launching a drone like those the Air Force uses. More advanced models would follow until they are ready to build one that can launch a small satellite into orbit. 38

  40. What is a true example of levitation? A) magic carpet B) A magician C) A magnetic train D) A helicopter hovering

  41. How does the Superman ride work? A) A rocket B) A lift chain C) Magnetic fields D) Differences in pressure

  42. Uses of Magnetism • Levitation • Forces Through a Magnetic Field • Earth Magnetic Field • The Sun

  43. Magnetic Forces on Moving Charged Particles If charge particles move in a magnetic field, they experience a sideways force

  44. Magnetic Forces on Current Carrying Wires • Moving electrons in wire are pushed up, or down, depending on their direction

  45. Measuring Currents • Coils of current-carrying wires set up magnetic field perpendicular to plane of coil • Compass needle aligns itself with the field lines

  46. Current-Measuring Apparatus • Electromagnet tends to align its north face with the iron magnet's south face • A spring resists this tendency to twist; the greater the current, the greater the deflection of the needle

  47. If current carrying wire travels through a magnet how does the current bend? A) Up B) Down C) Both D) Neither

  48. The direction of the magnetic force is always________ to both the magnetic field lines and the velocity of charged particle. A. Perpendicular B. Parallel C. There is no correlation D. Both parallel and perpendicular

  49. What decides whether the wires go up or down? A) Their direction B) Their mass C) Their energy D) Their speed

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