Electromagnets

• When a charged particle, such as a proton or electron, moves it causes a magnetic effect.
• When a current flows in a wire, it creates a circular magnetic field around the wire.
• The right hand grip rule is used to determine what direction a compass needle would face when held near a flowing current

  A) direction of current

  
• A solenoid consists of a wire coiled up into a spiral shape. When an electric current flows, the shape of the magnetic field is very similar to the field of a bar magnet.
• If there is a flat circular coil of wire, there will be ellipses of magnetic field lines around the coil
• The magnetic effect of a solenoid increases if:

  • Current in wire is increased
  • Number of loops of wire
  • If length decreases while number of loops stays same
  • Iron core is added inside the solenoid
• For solenoids and straight wires, if the current is flipped the other way, so does the direction of the magnetic field lines
• Direct current - current that only flows in one direction