Light Miscellany

 Rainbows What Causes them?t
 About Rainbows

UV  An experiment to detect its presence.  Tonic water responds to UV.  Add a blacklight to this exp for added evidence.

The Nature of Light  
 

I. LIGHT IS ELECTROMAGNETIC RADIATION

· LIGHT HAS WAVES
      --First an analogy:  Water waves behave like light waves  in circles, spreads, reflects;
· LIGHT HAS SPEED, FREQUENCY, WAVE LENGTH, AMPLITUDE
     --Recall Oersted & Faraday:  Electricity creates magnetism  Magnetism induces electricity
     --MAKING EM WAVES Battery & wire will create first current, then magnetic field, then electric f, then magnetic then elec. spreading out in 3 dimensions as waves
· LIGHT IS WAVES OF ELECTROMAGNETISM
     -- an invisible light  Can detect this "light" with a radio
· ELECTROMAGNETIC RADIATION:    LIGHT IS MADE BY A VIBRATING ELECTRIC CHARGE
 

II. THERE ARE DIFFERENT TYPES OF ELECTROMAGNETIC RADIATION  - LIGHT

 
8 Types of Electromagnetic Radiation
Radio
Microwave
Infrared
Visible
Ultraviolet
X-ray
Gamma ray
Cosmic
A. RADIO
    -- 3 hertz by hand moving a charged tuning fork-- tuning fork for 128 or 512  Hz
· A QUARTZ CRYSTAL VIBRATES FOR RADIO STATIONS
· AM  500-1600 KHz   FM  88-108 Mhz
· RADIO WAVES ARE MADE IN SPACE
B.  MICROWAVE
· RADAR is a kind of microwave
· FASTER VIBRATIONS BY TINY quartz CRYSTALS (<.02cm) or resonance of jumping electrons in magnetron
· YIELD MICROWAVES OF 109 Hz
 
C. INFRARED
  -- FELT AS HEAT ON SKIN  HOTPLATE DEMO
· USES: THERMOGRAPH  SATELLITE PHOTOS:  LAVA, MINERALS, VEGET, DISEASED PLANTS, SNAKES, MISSILES, IR SIGNATURE
· CAUSED BY VIBRATIONS OF SOMETHING SMALLER THAN CRYSTALS, - MOLECULES  OF MATTER
· 1013 Hz
· ALL MATTER HAS HEAT, VIBRATES, SO GIVES OFF IR
· HIGHER THE TEMP THE HIGHER THE FREQUENCY EMITTED
 
D. VISIBLE
·  Our world of beauty, information and action
· MOTION BY something still smaller -  OUTER ELECTRONS OF ATOMS Jump & Fall
· 4 X 1014 TO 7 X 1014   RED TO VIOLET
 
E. ULTRAVIOLET
· fluorescent light, Used to kill bacteria
· ELECTRONS  Jump & Fall To HIGHER LEVELS
·  blacklight  UV causes tan, skin cancer, wrinkles
 THE HIGHER THE FREQUENCY OF LIGHT THE MORE ITS ENERGY
 
F. X-RAYS
· Used to penetrate soft tissue for x-rays;
· 70kV ACCELERATED ELECTRONS RAPIDLY SMASH TO A STOP - the target gives off x-rays as its inner electrons are knocked off then fall back down.
· INNER ELECTRONS Jump & Fall
· blocked by bones
How x-ray machines work
l
G. GAMMA RADIATION
· SPLITTING OF NUCLEI OF ATOMS converts Matter directly to energy
·  part of radioactivity of nuclear blasts or radiation
·  Medical treatment of cancer
 
H. COSMIC RAYS
· NUCLEI PARTS AT FASTER RATES STILL  FROM SUN & SUPERNOVAS & OUTER SPACE
·  Higher energy than anywhere on earth
· Source of mutations on earth
·   f  about 1023 Hz
 

III. CONCLUSIONS

· DIFFERENT RATES OF VIBRATION MAKE DIFFERENT KINDS OF LIGHT
· THE HIGHER THE FREQUENCY OF LIGHT THE HIGHER ITS ENERGY
 


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