electromagnetism

• • When a current flows through a conducting wire a magnetic field is produced around the wire
  • The shape and direction ofthe magnetic field can be investigated using plotting compasses
  • The magnetic field is made up of concentric circles: A circular field pattern indicates that the magnetic field around a current-carrying wire has no poles
  • As the distance from the wire increases the circles get further apart: This shows that the magnetic field is strongest closest to the wire and gets weaker as the distance from the wire increases
• right hand thumb rule: thumb is the current, fingers are the magnetic field. Reversing the direction in which the current flows through the wire will reverse the direction of the magnetic field

  A) current

  B) field

  
• • If there is no current flowing through the conductor there will be no magnetic field
  • Increasing the amount of current flowing through the wire will increase the strength ofthe magnetic field: This means the field lines will become closer together

  A) top

  B) out

  C) towards

  D) into

  E) away

  
• Factors Affecting Field Strength

  • A larger current will produce a larger magnetic field and vice versa
  • The greater the distance from the conductor (ie wire), the weaker the magnetic field and vice versa
• label

  A) ellipses

  B) coil