Edexcel IGCSE Physics 复习笔记 6.1.8 Electromagnets

• When an electric current flows in a wire it creates a magnetic field around the wire
• By winding the wire into a coil we can strengthen the magnetic field by concentrating the field lines
• If this wire is wound around a soft magnet, such as an iron, then an electromagnet is made
  • The electromagnet is magnetic only when current flows through the wire

   

Electromagnets are made up of a coil of wire wrapped around an iron core

• The strength of an electromagnet’s magnetic field may be increased by:
  • Increasing the current in the coil
  • Adding more turns to the coil

   

• The magnetic field around an electromagnet has the same shape as the one around a bar magnet
• The field can be reversed by reversing the direction of the current
  • However, bar magnets are always magnetic, unlike electromagnets

转载自savemyexams