ELECTRO MAGNETIC WAVES

• Electromagnetic Waves


  They are also called EM waves or EM radiation

  They are created as a result of vibrations between an electric field and magnetic field
• Electromagnetic Spectrum


  Is a continuum of EM waves arranged according to wavelength or frequency
• Roman Men Invented Very Unusual Xray Guns

  Radio waves, Microwaves, Infrared, Visible light, Ultraviolet, Xray, Gamma Rays
• NON-IONIZING SPECTRUM (BUILDING SIZE)


  AM, FM TV, CELLPHONE, RADAR, TV REMOTE
• IONIZING SPECTRUM (ATOM SIZE)


  ULTRAVIOLET, X-RAYS, GAMMA RAYS
• LONG WAVELENGTH

  LOW FREQUENCY
• SHORT WAVELENGTH

  HIGH FREQUENCY
• PROPERTIES OF ELECTROMAGNETIC WAVES

  1. They are transverse waves. Electric and magnetic fields oscillate in a plane that is perpendicular to the propagation of the wave.
  2. EM waves are created by an oscillating charged particle, which creates an oscillating electric field and magnetic field.
  3. They do not require a medium to propagate. They can travel in a vacuum at a speed of 3 x 10^8 m/s = 300, 000, 000 m/s. It would take approximately 8 minutes for sunlight to reach Earth.
  4. The speed of EM waves changes depending on the medium where they are passing through.
• MECHANICAL WAVES


  require a medium to propagate. EM waves do not
• ELECTROMAGNETIC SPECTRUM
• WILLIAM GILBERT (1603)


  HE DISCOVERED THAT EARTH WAS MAGNETIC AND THEORIZED THAT ELECTRICITY AND MAGNETISM ARE NOT THE SAME. THE UNIT OF MAGNETIC POTENTIAL, GILBERT, WAS NAMED AFTER HIM.
• CHARLES AGUSTIN DE COULOMB (1785)


  HE DEVELOPED COULOMB'S LAW, WHICH DEFINED THE ELECTROSTATIC FORCE OF ATTRACTION AND REPULSION. THE SI UNIT OF CHARGE, COULOMB, WAS NAMED AFTER HIM.
• HANS CHRISTIAN OERSTED (1820)


  HE ACCIDENTALLY DISCOVERED THAT ELECTRICITY COULD PRODUCE MAGNETISM WHILE CONDUCTING AN EXPERIMENT IN HIS CLASS. OERSTED, A UNIT OF MAGNETIC INTENSITY, WAS NAMED AFTER HIM.
• JOSEPH HENRY (1831)


  FIRST TO DISCOVER ELECTROMAGNETIC INDUCTION, THE PRODUCTION OF AN ELECTRIC CURRENT ACROSS A CONDUCTOR MOVING THROUGH A MAGNETIC FIELD. THE SI UNIT FOR INDUCTANCE WAS NAMED AFTER HIM.
• WILHELM EDUARD WEBER (1856)


  HE DISCOVERED THAT THE RATIO OF ELECTROSTATIC TO ELECTROMAGNETIC UNITS EQUALS THE VALUE OF THE SPEED OF LIGHT, LEADING TO THE CONJECTURE THAT LIGHT IS AN EM WAVE. THE UNIT OF MAGNETIC FLUX, WEBER, WAS NAMED AFTER HIM.
• JAMES CLERK MAXWELL (1861) 


  HE DESCRIBED HOW ELECTRIC CHARGES AND CURRENTS ACT AS SOURCES OF ELECTRIC AND MAGNETIC FIELDS. HE FORMULATED EQUATIONS - MAXWELL'S EQUATIONS- WHICH SUMMARIZED THE RELATIONSHIP BETWEEN ELECTRICITY AND MAGNETISM.
• MAXWELL'S EQUATIONS

  1. Gauss' law
  2. Magnetic monopoles
  3. Faraday's law
  4. Ampere-Maxwell law
• ALBERT EINSTEIN (1905)


  HE FORMULATED THE CONCEPTS OF THE PHOTOELECTRIC EFFECT. HE WAS AWARDED THE 1921 NOBEL PRIZE IN PHYSICS FOR THE DISCOVERY OF THIS LAW.
• HEINRICH HERTZ (1887)


  HE PROVED THE EXISTENCE OF RADIO WAVES THROUGH HIS EXPERIMENTS. THE SI UNIT FOR FREQUENCY WAS NAMED AFTER HIM.