Electromagnets

• When a current flows through a conducting wire, a magnetic field is produced around the wire
• A larger current in a wire produces a stronger magnetic field
• The magnetic field is strongest closer to the wire
• What happens if you change the Direction of the current in a wire

  . We change the direction of the magnetic field (reversed the direction of the conventional current)
• how to work out direction of magnetic field produced by a wire

  . place right hand so that the thumb pointing in direction of conventional current

  . Fingers are pointing in direction of magnetic field
• A way to increase the strength of the magnetic field is to coil the wire (shape is called a solenoid)
• Three ways to increase strength of magnetic field produced by a solenoid

  . Increase size of current

  . increase number of turns of the coil

  . Place a piece of iron inside the solenoid
• A solenoid with an iron core is called an electromagnet