magnetic field

• A good application of magnets is a Magnetic Resonance Imaging Machine (MRI)
• MRI


  • Non-invasive machine that can image different parts of the body

  
• MRI uses strong permanent and superconducting magnets to generate a magnetic field that aligns with the body's hydrogen protons

  
• In this lesson, you will learn more about the properties of magnetic fields by visually representing them using field lines

  
• Magnetic field


  The area around a particular magnet where these behaviors are observed

  
• Magnetic field


  A vector quantity

  
• Magnetic field


  The direction can be determined using a compass
• Magnetometer


  Devices invented to measure the magnitude of magnetic fields

  
• Magnetometer


  • One of the first versions found in a geophysics observatory in Antarctica
• Magnetic field lines


  The behavior of magnetic fields can be visualized by sprinkling iron filings on a sheet of paper on top of magnets

  
• The magnetic field is directed from the north to the south pole, and has a stronger magnitude where the field lines are closer

  
• The arrangement of magnetic field lines is seen emerging from the north and south poles of a single magnet (horseshoe magnet)

  
• The figure shows the specific characteristics of magnetic field lines of a permanent magnet, as they pass from a magnet's interior to the magnetic field around it

  
• Characteristics of Magnetic Field Lines

  • Field lines are drawn such that each line through any point is tangential to the magnetic field vector
  • Field lines will never intersect since the direction of the magnetic field at each point is unique and distinct
  • They do not have endpoints. These lines continue through the magnet's interior
  • Since the lines are not directed into the force of a charge, they are not considered lines of force
  • In the case of uniform magnetic fields, magnetic poles are flat and are parallel with each other
  • For electrically-charged wires, the magnetic field is better represented on paper not by lines, but by dots and crosses
  • For an electrically-charged loop or a solenoid, the magnetic field is illustrated in the form of a typical loop, such as the one we have seen in bar magnets

  
• When there is no perpendicular component of the magnetic field B to the particle's velocity, no magnetic force is also present

  
• The area around a magnet where attraction and repulsion are observed is what is referred to as the magnetic field (B)

  
• Magnetic fields are signified by lines that show the direction of the magnetic force. These are called magnetic field lines

  
• Field lines are drawn such that each line through any point is tangential to the magnetic field vector at that point. Field magnitude is stronger where adjacent lines are closer, and grows weaker as the distance between lines become larger. They will never intersect since the direction of the magnetic field at each point is distinct