Electromagnetic waves and electro magnets

• Fleming's Left Hand Rule can be used to determine the direction of force on a wire carrying an electric current when placed in a magnetic field.
• The magnetic field lines are always perpendicular to the direction of flow.
• Magnetism is caused by moving charges or changing fields.
• Electricity is produced from magnetism using electromagnets.
• A generator converts mechanical energy into electrical energy using electromagnetic induction.
• How to determine the direction of the magnetic field lines, by using the direction of the current?

  Using the right hand thumb rule
• 4 ways to increase the magnetic field strength

  increasing current

  increase number of coils but keep the length the same

  decrease length but keep number of coils the same

  add and iron core
• what would happen to the poles and magnetic field if the current was reversed?


  The poles would switch sides and the magnetic field lines would flip around.
• How can we reverse the magnetic field lines?

  By reversing the current
• Why would adding an iron core be beneficial?

  It is a soft magnetic material. Which would gain magnetic field lines quickly and looses them as soon as current is switched off.
• Order of Em waves :

  
  

  1. radiowaves
  2. microwaves
  3. infrared
  4. visible light
  5. ultra violet
  6. x rays
  7. gamma rays
• radio waves are made by oscillating changes
• Radio waves are used for communication eg radio signals, bluetooth and tv
• Short radio waves can be received at long distances from the transmitter. That is because they are reflected from the ionosphere.( an electrically charged layer in the Earths upper atmosphere)
• Long radio waves can diffract around hills and tunnels
• Medium radio waves can also reflect from he ionosphere, depending on its atmospheric conditions and the time of day
• Micro waves are used by satellites and microwaves
• Infrared radiation can be used to monitor temperature of objects.

  the hotter the object the more IR it gives out.
• absorbing IR radiation can cause an object to become hotter e.g food
• Visible light is used to transmit data using fibre optic cables.
• Ultraviolet radiation can give u a suntan and cause skin cancer
• x-rays and gamma rays are used in medicines to see medical images and treat cancer