electromagnets

• How a current flowing through a wire generates a magnetic field

  1. Close the switch to allow current to flow through the wire

  2. A magnetic field is produced around the wire

  3. Strength of magnetic field depends on size of current

  4. Magnetic field is strongest closer to the wire

  5. Changing direction of current changes direction of magnetic field
• Right hand grip rule


  Place right hand so thumb points in direction of conventional current, fingers point in direction of magnetic field
• How a solenoid can increase the magnetic effect of a current

  1. Coil the wire to form a solenoid

  2. Turning on current produces strong, uniform magnetic field inside solenoid

  3. Magnetic field around solenoid similar to bar magnet
• Solenoid


  Coiled wire shape
• Electromagnet


  Solenoid containing an iron core
• Ways to increase strength of magnetic field in a solenoid

  • Increase size of current
  • Increase number of turns of coil
  • Place iron core inside solenoid