electromagnetism

• when a current flows through a conducting wire - magnetic field
• strength of magnetic field depends on the current through the wire and the distance from the wire
• solenoids

  • can increase strength of magnetic field by wrapping wire into a coil - field lines line up and are closer - stronger
  • increases strength by adding an iron core
• electromagnet

  • a solenoid with an iron core
  • the magnetic field can be turned on and off by a current
• uses

  • cranes in scrap yards
  • loudspeakers