PHYSICS

• Electromagnetic waves


  Waves that are created as a result of vibrations between an electric field and a magnetic field
• Wave


  A temporary disturbance that transfers energy from one place to another
• Types of waves

  • Mechanical waves
  • Electromagnetic waves
• Mechanical waves


  Waves in water and sound waves in air
• Medium


  Matter, such as solid, liquid, gas or plasma that mechanical waves are travelling through
• Electromagnetic waves


  Waves that do not require a medium to propagate, can travel through a vacuum
• How electromagnetic waves are formed

  1. Electric field comes in contact with a magnetic field

  2. Changing magnetic field induces electric field and vice-versa

  3. These changing fields form electromagnetic waves
• Electromagnetic waves

  • Electric field and magnetic field are perpendicular to each other
  • Electric field and magnetic field are also perpendicular to the direction of the EM wave
• EM waves travel with a constant velocity of 3.00 x 10^8 m/s in vacuum
• EM waves are capable of showing diffraction or interference
• Amplitude (A)


  • Height of a wave, usually measured in meters (m)
  • The greater the amplitude, the more energy it is carrying
• Wavelength (λ)


  The distance between 2 consecutive crests or troughs, usually measured in meters (m)
• Frequency (f)


  The number of waves passing a point in a certain time, measured in hertz (Hz)
• Speed of light (c) is about 3.00 x 10^8 m/s through a vacuum
• Wave equation


  1. Speed = frequency x wavelength

  2. Frequency = 1/time
• Types of electromagnetic waves

  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • Ultraviolet
  • X-ray
  • Gamma
• As you move from left to right of the EM Spectrum

  The wavelengths get smaller and the frequencies get higher
• Photons


  Mass-less particles that electromagnetic waves can be described as, each travelling in a wave-like pattern at the speed of light
• Energy


  Goes up as the frequency increases, energy is directly proportional to the frequency
• Ionizing and non-ionizing radiation

  • Non-ionizing radiation: radio waves, microwaves, infrared, visible light, ultraviolet
  • Ionizing radiation: gamma or X-rays
• The electromagnetic spectrum is a continuum of all electromagnetic waves arranged according to frequency and wavelength
• Electromagnetic waves


  Formed when an electric field comes in contact with a magnetic field
• Electromagnetic Waves


  Can be arranged according to wavelength, frequency, and energy
• Johann Carl Friedrich Gauss's Law


  A net amount of charge contained within a region of space will generate an electric field that emanates through the surface that surrounds that region
• Hanz Christian Oersted


  Electric current in a wire can deflect a magnetized compass needle
• André-Marie Ampère

  Discovered the force between two current carrying wires
• André-Marie Ampère's Law


  Magnetic field in space around an electric current is proportional to the electric current, just as the electric field in space is proportional to the charge
• Electric field


  • Inside a long solenoid
  • Inside a toroidal coil
  • From a long straight wire
  • Inside a conductor
• James Clerk Maxwell


  Developed a unified theory of electromagnetism
• Electromagnetic Theory


  • The force of attraction or repulsion between electric charges is inversely proportional to the square of the distance between them
  • Magnetic poles come in pairs that attracts and repels each other, much as electric charges do
  • An electric current in a wire produces a magnetic field whose direction depends on the direction of the current
  • A moving electric field produces a magnetic field, and vice versa
• Electromagnetic Force


  The force that light, electricity, and magnetism all come from, as proved by James Clerk Maxwell
• Heinrich Rudolf Hertz's Experiments


  Showed that the electromagnetic effects that Maxwell had identified propagated at a finite speed
• Heinrich Rudolf Hertz


  • Developed techniques for measuring the wavelength and velocity of electromagnetic waves and described their reflection and refraction
  • Discovered the existence of radio waves and determined that they behaved like light
• Max Karl Ernst Planck's Quantum Theory


  Energy is not continuous but quantized, and can only be transferred in individual "packets" or particles
• Photon


  The elementary particle, or quantum, of light
• Photon Absorption and Emission

  1. Photon absorbed, moved up an orbit

  2. Photon released, moved down an orbit
• Absorption Line Spectrum


  When a photon is absorbed, its energy is transferred to that atom or molecule
• Emission Line Spectrum


  When an atom or molecules loses energy, it emits a photon that carries an energy equals to the loss in energy of the atom or molecule
• Planck's Equation


  E = (h)(v), where E is the energy of the photon absorbed or emitted, v is the frequency of the photon, and h is Planck's constant
• Electricity and Magnetism are related, wherever charges are in motion electric current results, and magnetism is due to electric current