Physics 🪐

• Magnetic field


  The region around a magnet where a force may be felt
• Magnetic field


  • Invisible
  • Can be revealed with iron filings
• Investigating magnetic fields with iron filings

  1. Sprinkle iron filings around magnet

  2. Filings line up with magnetic field

  3. Take picture or draw pattern

  4. Carefully remove filings
• Investigating magnetic fields with plotting compasses

  1. Place magnet in centre of paper

  2. Place compass at end of magnet, slightly to side

  3. Mark where needle points

  4. Move compass so back of needle is on mark, mark other end

  5. Repeat until other end of magnet or paper

  6. Repeat from different position

  7. Join marks to show magnetic field
• Magnetic materials are iron, nickel and cobalt
• Magnets are surrounded by an invisible magnetic field
• Magnetic force is a non-contact force, objects don't need to touch to experience it
• The Earth has a magnetic field with a North and South Pole
• A compass needle is a small magnet that aligns with the Earth's magnetic field
• Safety precautions are important when using iron filings - wear goggles and contain filings
• Electromagnet


  A magnet formed by an electrical current. An electromagnet can be switched on and off.
• Electromagnet


  • Uses an electrical current to generate a magnetic field
  • Can be switched on and off
  • Can be made stronger or weaker
• Increasing the strength of an electromagnet

  1. Increasing the current through the wire

  2. Increasing the number of turns on the coil

  3. Adding a soft iron core
• Two magnets with the same poles


  Push each other away (repel)
• Two magnets with opposite poles


  Pull towards each other (attract)
• Motor effect


  The force on a current-carrying wire near a permanent magnet causes the wire to move
• Devices using the motor effect

  • DC motors
  • Loudspeakers
• Generator effect


  The wire moving near the magnet causes an electrical output
• Devices using the generator effect

  • Microphones
• Permanent magnet


  Always magnetic, has an invisible magnetic field
• Magnetic materials


  • Only certain materials, such as iron, feel a magnetic force
• Magnetic force


  Can be either an attraction (when forces pull objects towards each other) or a repulsion (when forces push objects away from each other)
• Magnetic field


  The region around a magnet where a force can be felt
• Permanent magnets


  • Can come in lots of different shapes and sizes, have a north (N) pole and a south (S) pole, magnetic field is shown by lines with arrows that point from north to south
• If you break a magnet in two, each half will still have two poles - north and south
• Magnetic materials


  Materials that feel a force from a magnetic field
• Magnetic materials are always attracted towards a magnet
• Bringing a north pole and a north pole together


  Causes the magnets to push away from each other or repel
• Bringing a north pole and a south pole together


  Causes the magnets to attract
• Earth's core contains liquid iron which moves around, causing Earth to have a magnetic field
• Compass


  An instrument used to navigate or find your way, with a magnetised needle that turns to line up with the Earth's magnetic field
• The north pole of a compass points towards the south pole of a magnet
• Earth's north pole is a magnetic south
• Earth's magnetic field protects us from charged particles thrown out from the Sun, deflecting them, and allowing them to reach the atmosphere near the poles, causing the Aurorae