chapter 5

• Magnet


  Any material that produces a magnetic force (push or pull) on a magnetic material such as iron

  
• Magnetism


  A force generated in matter by the motion of electrons within its atoms
• Magnetic field


  The region in space that is penetrated by imagining lines of magnetic force

  
• The history of magnetism dates back to

  Early than 600 BC
• Lodestone


  • Consists of iron oxide, a chemical compound of iron and oxygen
  • First observed form of the mineral magnetite
• Magnet (Ancient Greek)

  The mineral lodestone
• William Gilbert (1540-1603)


  • First to investigate the phenomenon of magnetism systematically using scientific methods
  • Discovered that the Earth is itself a weak magnet
• Carl Friedrich Gauses (1736-1806)


  • Conducted early theoretical investigations into the nature of Earth's magnetism
• Andre Marie Ampere (1775-1836) and Michael Faraday (1791-1869)


  • Conducted experiments involving the effects of magnetic and electric field on one another
• Madame Marie Curie (1867-1934)


  • Examined the effect of temperature on magnetic materials and observed that magnetism disappeared suddenly in certain materials like iron
• Origin of magnetism

  • Caused by electron orbits around the nucleus and spins around its axis, similar to the rotation of Earth around its own axis
  • Paul Exclusion Principle - each electronic orbit can be occupied by only two electrons of opposite spin
  • Transition metal atoms like iron, cobalt, and nickel are examples of magnetic materials
• Types of magnetism

  • Ferromagnetism
  • Ferrimagnetism
  • Antiferromagnetism
  • Paramagnetism
  • Diamagnetism

  
• Ferromagnetism


  A strong form of magnetism that occurs with the parallel alignment of equal magnetic moments

  
• Ferrimagnetism


  A strong form of magnetism that occurs with antiparallel alignment of unequal magnetic spins

  
• Antiferromagnetism


  A form of magnetism in which the magnetic moments of neighboring atoms are arranged anti-parallel
• Paramagnetism


  A property of certain materials that are weakly attracted to magnetic fields, with internal induced magnetic fields forming in the same direction as the applied field
• Diamagnetism


  Diamagnetic materials usually get repelled from a magnet, creating an induced magnetic field in a direction opposite to an externally applied magnetic force
• Magnetometer and Gaussmeter


  Used to measure magnetic field

  
• Attractive property


  Magnet attracts ferromagnetic materials like, iron, cobalt and nickel
• Directive property


  A freely suspended magnet always points in a north-south direction
• Natural magnets


  • All natural magnets are permanent magnets, meaning they will never lose their magnetic power
  • Natural magnets can be found in sandy deposits in various parts of the world
  • The strongest natural magnet material is lodestone, also called magnetite
• Artificial magnets


  • Magnets that are made by humans from magnetic substances
  • They can be made in different shapes and sizes like a bar magnet, horseshoe magnet, etc.
• Types of magnets


  • Permanent Magnet
  • Temporary Magnet
  • Electromagnetic
• Permanent magnet


  Are those magnets that are commonly used they are known as permanent magnet because they do not lose their magnetic property once they are magnetized
• Temporary magnet


  Can be magnetized in the presence of a magnetic field. When the magnetic field is removed, these materials lose their magnetic property, iron nails and paper clips are an examples of the temporary magnet
• Electromagnet


  Consist of a coil of wire wrapped around the metal core made from iron. When this material is exposed to an electric current, a magnetic field is generated, making material behave like a magnet
• Attractive property


  Magnet attracts ferromagnetic materials like, iron, cobalt and nickel
• Directive property


  A freely suspended magnet always points in a north-south direction
• Repulsive property


  Like magnetic poles repel each other and unlike magnetic poles attract each other
• Natural magnets


  • All natural magnets are permanent magnets, meaning they will never lose their magnetic power
  • Natural magnets can be found in sandy deposits in various parts of the world
  • The strongest natural magnet material is lodestone, also called magnetite
• Artificial magnets


  • Magnets that are made by humans from magnetic substances
  • They can be made in different shapes and sizes like a bar magnet, horseshoe magnet, etc.
• Types of magnets

  • Permanent Magnet
  • Temporary Magnet
  • Electromagnetic
• Permanent magnet


  Are those magnets that are commonly used they are known as permanent magnet because they do not lose their magnetic property once they are magnetized
• Temporary magnet


  Can be magnetized in the presence of a magnetic field. When the magnetic field is removed, these materials lose their magnetic property, iron nails and paper clips are an examples of the temporary magnet
• Electromagnet


  Consist of a coil of wire wrapped around the metal core made from iron. When this material is exposed to an electric current, a magnetic field is generated, making material behave like a magnet
• Like magnetic poles repel each other and unlike magnetic poles attract each other
• Information Technology

  The transmission of information requiring the use of systems specifically computers, and telecommunications, for storing, retrieving and sending information
• Information Communication Technology (ICT)

  The convergence of telecommunication networks with computer networks through telephone service with the computer network or Internet utilized a link system later known as fiber optics
• ICT

  • Covers storage, retrieval, manipulation and transmission of information in a digital form
  • Utilises desktops, emails, podcast, vodcast, cloud storage and the like
• Cloud Computing

  The usage of computing services through a software as well as hardware, provided as a service over a network which is the Internet