Physics

Physics

1. Light sources and the electromagetic spectrum

   • Colour mixing: When light is separated, the visible spectrum is displayed: All the colours we see in a rainbow are now visable. Red,Orange,Yellow,Green,Blue, Indigo, Violet
     • The three primary colours are red, blue, and green
       • Your eye has three "cone" nerve cells that detect those three colours, when all three are mixed white light is seen. When two of those colours are mixed the secondary colours of light are produced which are Magenta, cyan, and yellow. Mixing two complementary colours produces white as well. ex. magenta + green= white
         • subtractive and additive colour mixing
     • incandescence: light produced when an object gets hot.
     • Triboluminescence : Produced when certain crystals are scratched.
     • LEDs:electronic device that produces light when an electrical current passes through it.
     • Phosphorescence – Light from phosphorescent chemicals.
   • Light is a wave
     • light is visable form of energy that does not need a medium to travel through
   • The electromagnetic spectrum is the classification of electromagnetic waves based on the wave energy
     • Radio waves ex. telecommunications, microwaves ex. microwave ovens/big bang, infared radiation ex. lasers/remote control/keeps food warm , visable light , ultraviolet, X rays, gamma rays
       • These waves travel through the electromagnetic field
       • Lasers: special light source that emit Em waves of the same frequency
         • LASERs can burn precise holes in steel, used for surgery
       • Travels in wavelengths
         • Frequencies with larger wavelengths travel through mediums faster
   • Chemiluminescence: Light emitted by mixture of chemicals
     • Bioluminescence: Same as chemiluminescence, but occurring in living organisms.
   • S – Size of image A – Attitude of image L – location of image T – type of image

2. Reflection

   • visible light travels as an electromagnetic magnetic wave (electric and magnetic components
   • curved mirrors are seen in satelite dishes
     • works the same as a searchlight
   • Incident light is light emitted from a source that strikes an object.
     • Transparent,Translucent,opaque
     • Specular & diffuse reflection
   • virtual image, real image
     • Concave, convex mirrors
       • converging mirror. diverging mirror

3. Refraction

   • mirage: virtual image created by
   • Light bends through a prism because of refraction red is slowed down a little violet a lot
     • When light is slowed down, it bends away from its original path. The slower it’s forced to go, the more it bends.
       • Astronomers now use instruments to detect other forms of EM waves being given off by objects in outer space such as UV and radio.
         • objects can absorb and reflect certain wavelengths of visible light
           • spectrum of light reflected off these objects, there are dark lines this = absorption spectrum
             • light given off by the object’s= emmison spectrum
               • Sun reflects all light except for hydrogen and lithium
                 • sun is luminous produces its own light
   • Total Internal Reflection, trapping light

4. Electric Discharge:produced by passing electric current through a gas. ex.lightning