magnetism and electromagnetism

• magnet


  any material/object that produces a magnetic field
• what are the 2 poles

  north and south
• what direction does the magnetic field lines go

  from north into south
• North Pole and North Pole repel
• South Pole and South Pole repel
• South Pole and North Pole attract
• what can you use a compass for

  to figure out the North and South Pole of a magnet
• is the magnetic field stronger at the poles or the middle of the magnet

  the magnetic field is stronger at the poles as there are more lines closer together
• magnetic material 


  any object that can be influenced by magnetic field(it has potential to become a magnet)
• what are magnetic materials


  nickel (only some), cobalt, iron, steel
• permanent magnet 


  produce their own magnetic field all the time
• an example of a permanent magnet

  bar magnet
• induced magnet


  only have magnetic fields temporary
• what do forced between permanent and induce magnets do

  attract
• an example of a material that can be turned into an induced magnet

  nickel
• what is a magnetically soft material

  a material that looses magnetism quickly
• an example of a magnetically soft material

  nickel and iron
• what is a magnetically hard material

  a material that looses magnetism slowly
• an example of a magnetically hard material

  steel
• what is an electromagnet

  only magnetic for as long as you keep the current flowing
• 4 ways to increase strength

  increase current, number of coils, reduce length of solenoid, add iron core
• what is the motor effect

  a current carrying wire in the presence of a magnetic field will experience a force
• how to calculate he strength of force

  force(n)=magnetic flux density(T)X Current(A)X length of wire(M)
• what does your thumb tell you in flemings left hand rule

  Direction of force
• What does your middle finger tell you in flemings left hand rule

  Direction of current
• What does your index finger tell you in flemings left hand rule

  Direction of magnetic field
• What concept describes the force on a current-carrying wire in a magnetic field?

  The motor effect
• What determines the direction of the force on a wire in a magnetic field?

  The directions of the magnetic field and current
• How can you determine the direction of force on a wire using Fleming's rule?

  By using Fleming's left hand rule
• What happens to the force direction if the current direction in a wire is reversed?

  The force direction also reverses
• What occurs when two wires in a magnetic field have currents flowing in opposite directions?

  • One wire experiences an upward force
  • The other wire experiences a downward force
• What happens to the coil when the current flows from the positive terminal to the negative terminal?

  The coil starts to spin clockwise
• What occurs to the forces acting on the coil after it is rotated by 180 degrees?

  The forces swap directions on each side
• Why does the coil not rotate 360 degrees without intervention?

  It keeps flipping back and forth
• What device is used to change the direction of current every half turn in a motor?

  A split ring commutator
• What is the function of the split ring commutator in a motor?

  It swaps positive and negative connections
• How does the split ring commutator affect the direction of forces on the coil?

  It ensures forces act in the same direction
• What happens when the positive terminal is connected to one side of the commutator?

  The coil experiences clockwise forces
• What are some common applications of electric motors?

  • Fans
  • Vehicles
  • Hard drives
• What is necessary for most motors to function effectively in real life?

  They need to be more powerful