Light & Electromagnetic waves  Jitesh Aggarwal  XII Science (2011-12) FAITH ACADEMY
A light  review: <ul><li>Our primary source of light is the  sun . </li></ul><ul><li>Light travels in straight lines at a ...
Sensing Light <ul><li>Humans have two light detectors. </li></ul><ul><li>Do you know what they are called? </li></ul>Did y...
What is light really? Elec trom agne tic   radi atio n   wa ves   <ul><li>Light waves are three dimensional </li></ul><ul>...
*Electromagnetic Radiation <ul><li>E l ectromagnetic radiation  can be described in terms of a stream of  photons.  Each p...
 
 
Remember radio waves are long…and gamma rays are small Radio-TV -Microwave- Infrared - VISIBLE -Ultraviolet -X-rays - Gamm...
Radio (Longest  electromagnetic waves) <ul><li>Emitted by </li></ul><ul><ul><li>Astronomical Objects </li></ul></ul><ul><u...
Television <ul><li>Shorter than radio, also used to carry messages (pictures & sound) to our TV sets. </li></ul><ul><li>* ...
Microwave <ul><li>Emitted by: </li></ul><ul><ul><li>Gas clouds collapsing into stars </li></ul></ul><ul><ul><li>Microwave ...
Infrared (Heat or Thermal) Are you a source of infrared?  YES you are! <ul><li>Emitted by </li></ul><ul><ul><li>Sun and st...
Let’s take a look at  Herschel’s Experiment <ul><li>Herschel’s Experiment </li></ul><ul><ul><li>Discovered Invisible Light...
Let’s set up Herschel’s Experiment <ul><li>Set up of Box Design for Conducting the Herschel Experiment. </li></ul>
Conducting Hershel’s Experiment <ul><li>Place a sheet of white paper inside a cardboard box </li></ul><ul><li>Tape three t...
Visible Eac h   co lor   is   a differe nt   si ze   w ave . Red the longest   &  violet the shortest <ul><li>Emitted by <...
Prism Power:  R o y  G .  B i v  Activity <ul><li>*What happens when light shines through prisms? </li></ul><ul><li>Materi...
 
Ultraviolet Sunburn / black light <ul><li>Emitted by </li></ul><ul><ul><li>Tanning booths (A) </li></ul></ul><ul><ul><li>T...
X-ray <ul><li>Emitted by </li></ul><ul><ul><li>Astronomical objects  </li></ul></ul><ul><ul><li>X-ray machines </li></ul><...
Chandra X-ray Observatory <ul><li>Chandra is designed to observe X-rays from high energy regions of the universe, such as ...
Gamma Ray (Short electromagnetic waves but more energetic) <ul><li>Emitted by </li></ul><ul><ul><li>Radioactive materials ...
Sources of g-ray Emission <ul><li>•  Black holes </li></ul><ul><li>•  Active Galaxies </li></ul><ul><li>•  Pulsars </li></...
COSMIC Rays ( The highest energy waves and the deadliest) <ul><li>Cosmic rays come from deep space and can pass through th...
<ul><li>A great question! </li></ul><ul><li>Radio waves= (Buildings to </li></ul><ul><li>human size); </li></ul><ul><li>Mi...
Upcoming SlideShare
Loading in …5
×

Light

1,246 views

Published on

Light

Published in: Education, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,246
On SlideShare
0
From Embeds
0
Number of Embeds
3
Actions
Shares
0
Downloads
53
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Light

  1. 1. Light & Electromagnetic waves Jitesh Aggarwal XII Science (2011-12) FAITH ACADEMY
  2. 2. A light review: <ul><li>Our primary source of light is the sun . </li></ul><ul><li>Light travels in straight lines at a speed of 186,000miles per second. </li></ul><ul><li>Light waves travel faster than sound waves. </li></ul><ul><li>Light energy from the sun travels through space , reaches earth, and some of it turns to heat energy and warms the earth’s air. </li></ul><ul><li>Light from the sun also travels to the cells of green plants (producers ) and is stored as energy. </li></ul><ul><li>When light reaches an object, it is absorbed, reflected, or passes through it. </li></ul>
  3. 3. Sensing Light <ul><li>Humans have two light detectors. </li></ul><ul><li>Do you know what they are called? </li></ul>Did you realize cameras and camcorders are light detectors too?
  4. 4. What is light really? Elec trom agne tic radi atio n wa ves <ul><li>Light waves are three dimensional </li></ul><ul><li>Light waves vibrate in all planes around a center line. </li></ul><ul><li>The waves have high points called “ crests.” </li></ul><ul><li>Waves also have low points called “ troughs .” </li></ul><ul><li>*The distance from one crest to the next crest is called a “ wavelength .” </li></ul><ul><li>*The number of waves passing a given point in one second is called the “frequency .” </li></ul>wavelength
  5. 5. *Electromagnetic Radiation <ul><li>E l ectromagnetic radiation can be described in terms of a stream of photons. Each photon is traveling in a wave-like pattern, moving at the speed of light and carrying some amount of energy. </li></ul><ul><li>The only difference amongst radio waves, visible light, and gamma-rays is the amount of energy of the photons. Radio waves have photons with low energies. Microwaves have a little more energy than radio waves. Infrared has still more energy. </li></ul><ul><li>As we move down the chart we see visible , ultraviolet , X-rays , and gamma-rays whose photon energies gradually increase. </li></ul><ul><li>Gamma and Cosmic rays have the highest energy waves. </li></ul>
  6. 8. Remember radio waves are long…and gamma rays are small Radio-TV -Microwave- Infrared - VISIBLE -Ultraviolet -X-rays - Gamma- Cosmic
  7. 9. Radio (Longest electromagnetic waves) <ul><li>Emitted by </li></ul><ul><ul><li>Astronomical Objects </li></ul></ul><ul><ul><li>Radio Station Transmitters </li></ul></ul><ul><li>Detected by </li></ul><ul><ul><li>Ground based radio telescopes </li></ul></ul><ul><ul><li>*If you turn on a radio,, it will convert the radio wave energy into sound energy. </li></ul></ul>
  8. 10. Television <ul><li>Shorter than radio, also used to carry messages (pictures & sound) to our TV sets. </li></ul><ul><li>* We can sense the TV waves around us with our televisions. </li></ul>
  9. 11. Microwave <ul><li>Emitted by: </li></ul><ul><ul><li>Gas clouds collapsing into stars </li></ul></ul><ul><ul><li>Microwave Ovens </li></ul></ul><ul><ul><li>Radar Stations </li></ul></ul><ul><ul><li>Cell Phones </li></ul></ul><ul><li>Detected by </li></ul><ul><ul><li>Microwave Telescopes </li></ul></ul><ul><ul><li>Food (heated) </li></ul></ul><ul><ul><li>Cell phones </li></ul></ul><ul><ul><li>Radar (systems) </li></ul></ul>
  10. 12. Infrared (Heat or Thermal) Are you a source of infrared? YES you are! <ul><li>Emitted by </li></ul><ul><ul><li>Sun and stars (Near) </li></ul></ul><ul><ul><li>TV Remote Controls </li></ul></ul><ul><ul><li>Food Warming Lights (Thermal) </li></ul></ul><ul><ul><li>*Everything at room temperature or above,=HEAT </li></ul></ul><ul><li>Detected by </li></ul><ul><ul><li>Infrared Cameras </li></ul></ul><ul><ul><li>TVs, VCRs, </li></ul></ul><ul><ul><li>Your skin </li></ul></ul>
  11. 13. Let’s take a look at Herschel’s Experiment <ul><li>Herschel’s Experiment </li></ul><ul><ul><li>Discovered Invisible Light </li></ul></ul><ul><ul><li>In 1800, Herschel places his control thermometer just outside the red end of the spectrum </li></ul></ul><ul><ul><li>Result: The outside thermometer registered the highest temperature </li></ul></ul>
  12. 14. Let’s set up Herschel’s Experiment <ul><li>Set up of Box Design for Conducting the Herschel Experiment. </li></ul>
  13. 15. Conducting Hershel’s Experiment <ul><li>Place a sheet of white paper inside a cardboard box </li></ul><ul><li>Tape three thermometers together and place inside box </li></ul><ul><li>Cut a small notch in the top of the box and position a glass prism so that the spectrum is projected inside the box </li></ul><ul><li>Arrange the thermometers so that one is just outside the red end of the spectrum, with no visible light falling on it </li></ul>
  14. 16. Visible Eac h co lor is a differe nt si ze w ave . Red the longest & violet the shortest <ul><li>Emitted by </li></ul><ul><ul><li>The sun and other astronomical objects </li></ul></ul><ul><ul><li>Laser pointers </li></ul></ul><ul><ul><li>Light bulbs </li></ul></ul><ul><li>Detected by </li></ul><ul><ul><li>Cameras </li></ul></ul><ul><ul><li>(film or digital) </li></ul></ul><ul><ul><li>Human eyes </li></ul></ul><ul><ul><li>Plants (red light) </li></ul></ul><ul><ul><li>Telescopes </li></ul></ul>RoyG.Biv
  15. 17. Prism Power: R o y G . B i v Activity <ul><li>*What happens when light shines through prisms? </li></ul><ul><li>Materials :prism, PASCO “wave it,”equipment, paper, +7 R o y G . B i v crayon colors, </li></ul><ul><li>1. Give handouts. Darken the room and turn on light source. What color is the light? If I use a prism can you predict what will happen to the light? </li></ul><ul><li>2.Now use the prism. What color is the light? </li></ul><ul><li>3. Color in your hand out to match the spectrum. </li></ul>*PASCO Probe Activity OR *AIMS:Primarily Physics: Prism Power Activity
  16. 19. Ultraviolet Sunburn / black light <ul><li>Emitted by </li></ul><ul><ul><li>Tanning booths (A) </li></ul></ul><ul><ul><li>The sun (A) </li></ul></ul><ul><ul><li>Black light bulbs (B) </li></ul></ul><ul><ul><li>UV lamps </li></ul></ul><ul><li>Detected by </li></ul><ul><ul><li>Space based UV detectors </li></ul></ul><ul><ul><li>UV Cameras </li></ul></ul><ul><ul><li>Flying insects (flies) </li></ul></ul>He can get skin cancer!
  17. 20. X-ray <ul><li>Emitted by </li></ul><ul><ul><li>Astronomical objects </li></ul></ul><ul><ul><li>X-ray machines </li></ul></ul><ul><ul><li>CAT scan machines </li></ul></ul><ul><ul><li>Older televisions </li></ul></ul><ul><ul><li>Radioactive minerals </li></ul></ul><ul><ul><li>Airport luggage scanners </li></ul></ul><ul><li>Detected by </li></ul><ul><ul><li>Space based X-ray detectors </li></ul></ul><ul><ul><li>X-ray film </li></ul></ul><ul><ul><li>CCD detectors </li></ul></ul>
  18. 21. Chandra X-ray Observatory <ul><li>Chandra is designed to observe X-rays from high energy regions of the universe, such as the remnants of exploded stars. </li></ul><ul><li>The most sophisticated observatory built to date. </li></ul><ul><li>Deployed by the Space Shuttle Columbia on July 23, 1999, </li></ul>Chandra X-ray Observatory
  19. 22. Gamma Ray (Short electromagnetic waves but more energetic) <ul><li>Emitted by </li></ul><ul><ul><li>Radioactive materials </li></ul></ul><ul><ul><li>Exploding nuclear weapons </li></ul></ul><ul><ul><li>Gamma-ray bursts </li></ul></ul><ul><ul><li>Solar flares </li></ul></ul><ul><li>Detected by </li></ul><ul><li>-- Geiger counters </li></ul><ul><ul><li>Gamma detectors and astronomical satellites </li></ul></ul><ul><ul><li>Medical imaging detectors </li></ul></ul>
  20. 23. Sources of g-ray Emission <ul><li>• Black holes </li></ul><ul><li>• Active Galaxies </li></ul><ul><li>• Pulsars </li></ul><ul><li>• Diffuse emission </li></ul><ul><li>• Supernovae </li></ul><ul><li>Gamma-ray bursts </li></ul><ul><li>• Unidentified </li></ul>
  21. 24. COSMIC Rays ( The highest energy waves and the deadliest) <ul><li>Cosmic rays come from deep space and can pass through the Earth. </li></ul>
  22. 25. <ul><li>A great question! </li></ul><ul><li>Radio waves= (Buildings to </li></ul><ul><li>human size); </li></ul><ul><li>Microwaves </li></ul><ul><li> (Humans-beetles); </li></ul><ul><li>Infrared waves </li></ul><ul><li>(Eye of a needle); </li></ul><ul><li>Visible waves </li></ul><ul><li>(microscopic size)! </li></ul><ul><li>WOW! All the rest are the size of molecules, atoms, atomic nuclei and smaller.. </li></ul>How big are the waves?

×