SNC 2D1 UNIT 9/10

• Types of Electromagnetic Waves

  • Radio waves
  • Microwaves
  • Infrared Waves
  • Ultraviolet Rays
  • X-Rays
  • Gamma Rays
• Radio waves

  • Magnetic resonance imaging (MRI) medical imaging machines
  • Television signals
  • Cellphones
• Microwaves

  • Radars that measure the speed of automobiles and monitor aircraft flight
• Infrared Waves

  • Burglar alarms
  • Motion sensors
  • Night vision goggles
• Ultraviolet Rays


  • Disinfect drinking water
  • Disinfect waste water
  • DNA analysis
• X Rays

  • X-ray medical imaging
  • Airport luggage security measures
  • Photographing to check machine damages
• Gamma Rays


  • Used by doctors in short burst to kill a certain number of cancerous cells
• Colours associated with visible light

  • Red
  • Orange
  • Yellow
  • Green
  • Blue
  • Indigo
  • Violet
• The colour sequence is called the visible spectrum
• A triangular prism is used to split white light into its components (ROY G BIV) known as splitting light
• Reflection


  The process in which light "bounces off" a surface and changes direction
• Absorption


  The process in which light energy remains in the object it hits
• Transmission


  When a wave (like light) travels through a medium
• Transparent


  See through, light passes right through the object
• Translucent


  Cannot quite see right through it; transmits some light, absorbs and reflects some light
• Opaque


  No light can pass through, material absorbs and reflect all light
• Law of reflection


  • The angle of reflection (r) is equal to the angle of incidence (i)
  • The incident ray, the normal and the reflected ray lie on the same plane (any flat surface)
• Smooth surface reflection


  • Normals are all parallel
  • Reflected rays bounce off the surface with the same angle as the incident rays
• Rough surface reflection


  • Normal lines point in different directions
  • Incident rays are parallel to each other, but the angles of incidence are different
• Ray diagrams


  Pictorial representations of how light travels to form an image
• Ray diagram SALT characteristics descriptions

  • Size of an image: same size, smaller, or larger than object
  • Attitude of Image: Orientation of image compared to object (upright or inverted)
  • Location of Image: Behind mirror or same side of object
  • Type of image: Real or virtual
• Virtual image

  An image which light does not arrive at or come from the image location
• Real image

  An image that can be seen with the human eye or can be displayed since light rays arrive at the location of the image
• Plane mirrors


  • Flat reflecting surfaces on which regular reflection is observed
  • Rays from the object striking the plane mirror will be reflected according to the law of reflection
  • Create a virtual image (rays that reach your eye appear as if they are coming from behind the mirror)
• Plane mirror image SALT characteristics

  • Size: Same size as the object size
  • Attitude: Upright orientation
  • Location: image is the same distance behind mirror as object in front
  • Type: Virtual image
• Light

  Energy that travels like an electromagnetic wave visible to the human eye
• Properties of light


  • Travels in straight lines
  • Travels at a high speed
  • Travels through the vacuum of space
• C is the symbol for the speed of light in a vacuum, and its value is defined as 3 x 10^8 m/s
• Sources of visible light

  • Incandescent
  • Fluorescence
  • Phosphorescence
  • Chemiluminescence
  • Triboluminescence
  • Electrical Discharge
  • Electroluminescence
  • OLEDS
  • Plasma Display
  • Liquid Crystal Display
• Incandescent

  Light produced by an object
• Fluorescence

  Light emitted from a substance when exposed to electromagnetic radiation
• Phosphorescence

  Emits light only when exposed to ultraviolet radiation
• Chemiluminescence

  Produced from chemical reactions without a rise in temperature
• Triboluminescence

  Light produced from friction
• Electrical Discharge

  Produced when electric current passes through air or another gas
• Electroluminescence

  Transformation of electrical energy directly into light energy
• OLEDS

  Several extremely thin layers of organic molecules that use electrical currents to produce coloured light (use less energy)
• Plasma Display

  Ultraviolet radiation absorbed by phosphors that radiate light in the visible spectrum
• Liquid Crystal Display

  When light shines behind a liquid crystal
• Waves + Properties of a Wave

  • Disturbance that transfers energy from one point to another without transferring matter
  • Crest: Highest point
  • Trough: Lowest point
  • Rest Position: Position of the medium when no waves are travelling through
  • Amplitude: Wave height from rest position to the crest
  • Wavelength: Distance from one place in the wave to the next similar place
  • Frequency: Rate of repetition of a wave