Magnetism and electromagnetism

• All magnets have two poles

  1. North
  2. South
• All magnets produce a magnetic field which is a region where other magnets or magnetic materials experience a force
• Magnetic materials include iron, steel, nickel, and cobalt
• The magnetic field always goes north to south
• The closer together the magnetic field lines are, the stronger the magnetic field and the further away you are from a magnet, the weaker the field is
• The magnetic field is stronger at the poles of the magnets
• The force between a magnet and a magnetic materials is always attractive no matter the pole
• If two poles of a magnet are put near eachother, they both exert a force on eachother which can be attractive or repulsive. Two same poles (NN / SS) repel and two different poles (NS / SN) attract
• Inside a compass there's a tiny bar magnet where the north pole is attracted to the south pole so the compass points in the magnetic fields direction
• You can move a compass around a magnet and trace it's position on some paper to see the magnetic field
• When they're not near a magnet, compasses always point north and this is because earth has its own magnetic field so the earth's core must be magnetic
• Permenant magnets produce their own magnetic field
• Induced magnets are magnetic materials that become a magnet when placed in a magnetic field.
• When a current flows through a wire a magnetic field is created around the wire made up of concentric circles perpendicular to the wire
• When you place a compass near a wire that's producing a current and moved the compass, it will trace the direction of the magnetic field because changing the currents direction changes the fields direction
• The current is directly proportional to the magnetic field
• A solenoid is a coil of wire that produces a magnetic field around it.
• You can increase the strength of a magnetic field that a wire produces by wrapping the wire into a solenoid
• Wrapping a wire around a solenoid results in a lot of field lines pointing in the same direction very close to eachother and outside the coil the magnetic field is the same as a bar magnets
• You can increase the magnetic field of a solenoid by putting a block of iron in the centre of the coil as it becomes an induced magnet which is known as an electromagnet
• Electromagnet uses

  1. Cranes to attract and pick up magnetic materials as you can switch it off to drop it
  2. Used in circuits to act as switches
• The motor effect can happen when you put a current carrying wire in a magnetic field
• When a current carrying wire is placed between magnetic poles, the field around the wire interacts with the magnetic field it's been placed in which causes the wire and the magnet and conductor to exert a force on eachother causing the wire to move