Magnet

• Magnetic force is a non-contact force that is exerted around a magnet, in a magnetic field. It can be either push(repulsion) or pull(attraction).
• Induced magnetism is a temporary magnetism acquired by a magnetic material when it is placed near a magnet
• The strength of the induced magnetism depends on how close the object is to the permanent magnet.
• Magnetic materials : Cobalt, Nickel, Iron and steel
• When you draw a magnetic field, the arrows are always from north to south
• How to draw a magnetic fields

  1. Place a bar magnet and draw around it.
  2. Place the plotting compass at the pole of the bar magnet and make a dot where the red tip indicates.
  3. Move the compass tail to the new dot and repeat it until you reach the other pole.
  4. Draw a line through the dots.
• Magnetic field(force) is the strongest at the poles
• Electromagnet is a coil of insulated wire(copper, also called a solenoid) wrapped around an iron core which becomes magnetic when there is a current(flow of electrons) in the wire.
• Unlike permanent magnet, electromagnet can be switched on & off
• What happens when you turn an electromagnet on?

  If you turn the electromagnet on, there is a current in the coil. A magnetic force is produced around the coil, and the iron core becomes magnetized due to induced magnetism. So, the magnetic materials are attracted to the electromagnet.
• How to increase the strength of an electromagnet?

  1. Use a bigger current

  2. Use an iron core

  3. Make more turns of wire on your solenoid.