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Helpful Website: . http:// www.darvill.clara.net/emag/index.htm. Do Now. Take a clicker Take a Do Now; put aside. Take a POGIL – do the Warm Up#1-9 Homework: As always, whatever you did not finish in class becomes HW . (POGIL from today) Read & Study corresponding sections in Ch. 27.

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Helpful website

Helpful Website:

http://www.darvill.clara.net/emag/index.htm


Do now

Do Now

  • Take a clicker

  • Take a Do Now; put aside.

  • Take a POGIL – do the Warm Up#1-9

    Homework:

  • As always, whatever you did not finish in class becomes HW. (POGIL from today)

  • Read & Study corresponding sections in Ch. 27.

  • Do #11-17, 20-23(12 points – 1 per #, 1 correctness)


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Demo

  • Fill out the DO NOW portion of your chart


Overview of radiation

Overview of Radiation

  • Although scientists have only known about radiation since the 1890s, they have developed a wide variety of uses for this natural force.

  • Today, to benefit humankind, radiation is used in medicine, academics, and industry, as well as for generating electricity.

  • In addition, radiation has useful applications in such areas as agriculture, archaeology (carbon dating), space exploration, law enforcement, geology (including mining), and many others. 

  • Nrc.gov


Radio waves

Radio Waves

  • Used for communication

    • Radios

    • Cell phones

    • TV

    • Some forms of wifi

  • RADAR – Doppler effect from radio waves to image things


Microwave radiation

Microwave Radiation

  • Used for cooking

  • Also used for communication (similar to radio waves)

  • This is why some people say cell phones will give you brain cancer

  • Common sense: don’t take unnecessary risks

    • Keep wifi routers in areas where they aren't constantly next to people

    • Try not to sleep with your phone next to your head

    • Cell phones in pockets…?

    • Took decades for science to conclude that smoking was bad for human health…. May or may not find something similar with all of the ‘wireless’ technology aka radiation


Infrared radiation

Infrared Radiation

  • Given off by all warm objects and produce heat in all objects they strike.

  • The earth is warmed by infrared radiation from the sun.

  • Infrared lamps (incandescent lamps that emit mostly infrared radiation) are used for:

    • drying paint, wallpaper, and printing ink;

    • keeping food warm in restaurant kitchens;

    • providing warmth in outdoor waiting areas during cold weather; (Shake Shack)

    • for therapeutic heat treatments.

    • Remotes and lasers used to read CDs, DVDs, etc.

  • Face detection in cameras – more on this later!


Infrared radiation1

Infrared Radiation

  • Infrared radiation can be detected by various electronic devices which make it possible to obtain images of the infrared radiation reflected or produced by an object:

    • check the heat insulation of a building/windows,

    • identify sources of thermal pollution in bodies of water,

    • in medicine to detect abnormally warm areas of the body, revealing the location of diseased tissue.

    • In the military, as an aid in locating enemy troops at night,

    • and devices that detect infrared radiation emitted by aircraft are used to guide certain antiaircraft missiles.

    • In night vision goggles

    • and in mapping the distribution of vegetation and other resources on the earth's surface.


Visible light radiation

Visible Light Radiation

  • ROYGBIV

  • All we can see!


Uv radiation

UV Radiation

  • Emitted by the sun and UV bulbs;

  • Responsible for triggering skin to produce melanin and tan/burn;

  • Used to kill germs:

    • nail salons use them to sanitize equipment – they look like toaster ovens that glow purple.

    • Also, the goggle cabinet in the back of this room uses UV light

  • Used to detect counterfeit money,

    cards, and documents


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More on this next class!


Examples of uv damage

Examples of UV damage:


Examples of uv damage1

Examples of UV damage:


Examples of uv damage2

Examples of UV damage:


Skin cancer scars

Skin CancerScars


Uv cont

Localized skin cancer

UV cont.

A very bad case of skin cancer


X rays

X-Rays


X rays cont

X-Rays cont.

  • Injury to the skin and underlying tissues from acute exposure to a large external dose of radiation is referred to as cutaneous radiation injury (CRI).


X rays cont1

X-Rays were over used many years ago and people were gravely injured….See next slide.

X-Rays Cont.

Full Term fetus (what is wrong with this picture?)


X rays cont2

Over-exposed ankle

X-Rays cont.

Over exposure of the hand. This is an early x-ray technician’s hand.


Gamma radiation

Gamma radiation

  • Gamma Radiation has the shortest wavelength and the highest frequency in the EM spectrum.


Are wavelength and frequency directly or inversely proportional

Are wavelength and frequency directly or inversely proportional?

  • Directly

  • Inversely

  • Not sure


Gamma cont

Gamma cont.

  • Best known for the Hollywood blockbuster, “The Incredible Hulk”. This is of course, fiction!!!!!


Gamma cont hiroshima and nagasaki the atomic bombings and resultant biological effects of radiation

Gamma Cont. Hiroshima and Nagasaki: The Atomic Bombings and Resultant Biological Effects of Radiation


Gamma cont1

Most extreme

Gamma cont.

Alpha, beta and gamma penetration


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POGIL - Check in at stop signs! Not going over whole thing as a class!Stopping with 10 minutes left for a graded clicker exit


Generally speaking is it safer to be exposed to high or low frequency radiation

Generally speaking… is it safer to be exposed to high or low frequency radiation?

  • High

  • Low


Do high frequency em waves have any benefits

Do high frequency EM waves have any benefits?

  • Yes

  • No

  • Not sure


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Would you rather be exposed to Millimeter wave technology, or backscatter X ray technology, at the airport security checkpoints??

  • Millimeter wave

  • Backscatter X-Ray

  • Not sure


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27.7Polarization

Light that reflects at glancing angles from nonmetallic surfaces, such as glass, water, or roads, vibrates mainly in the plane of the reflecting surface.


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27.7Polarization

  • Light travels in waves. The fact that the waves are transverse—and not longitudinal—is demonstrated by the phenomenon of polarization.

    • If you shake the end of a horizontal rope, a transverse wave travels along the rope.

    • The vibrations are back and forth in one direction.

    • The wave is said to be polarized.

  • If the rope is shaken up and down, a vertically polarized wave is produced.

  • The waves traveling along the rope are confined to a vertical plane.

  • If the rope is shaken from side to side, a horizontally polarized wave is produced.


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27.7Polarization

  • A vibrating electron emits a polarized electromagnetic wave.

  • A vertically vibrating electron emits vertically polarized light.

  • A horizontally vibrating electron emits horizontally polarized light.


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27.7Polarization

An incandescent or fluorescent lamp, a candle flame, or the sun all emit light that is not polarized.

The electrons that produce the light vibrate in random directions.

BUT –

When light shines on a polarizing filter, the light that is transmitted is polarized.


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27.7Polarization

A rope analogy illustrates the effect of crossed sheets of polarizing material.


If polarized light tries to pass through a filter

If POLARIZED light tries to pass through a filter…


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27.8Polarized Light and 3-D Viewing

Besides sunglasses… what other uses of polarizing filters can you think of?


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27.8Polarized Light and 3-D Viewing

A pair of photographs or movie frames, taken a short distance apart (about average eye spacing), can be seen in 3-D when the left eye sees only the left view and the right eye sees only the right view.


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27.8Polarized Light and 3-D Viewing

A 3-D slide show uses polarizing filters. The left eye sees only polarized light from the left projector; the right eye sees only polarized light from the right projector.

Each eye sees a different image, and when the brain combines the images, you get a feeling of depth.


Does light travel in a transverse or longitudinal wave

Does light travel in a transverse or longitudinal wave?

  • Transverse

  • Longitudinal

  • Not sure


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Which pair of glasses is best suited for automobile drivers? (The polarization axes are shown by the straight lines.)

  • A

  • B

  • C

  • A & B

  • B & C

  • A B & C

  • None of the above


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27.8Polarized Light and 3-D Viewing

think!

Which pair of glasses is best suited for automobile drivers? (The polarization axes are shown by the straight lines.)

Answer:

Pair A is best suited because the vertical axes block horizontally polarized light that composes much of the glare from horizontal surfaces.


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Which pair of glasses is best suited for 3D movies? (The polarization axes are shown by the straight lines.)

  • A

  • B

  • C

  • A & B

  • B & C

  • A B & C

  • None of the above


Exit slip

Exit Slip

  • Please fill out the exit portion of your slip and turn in

  • CLICKERS RETURNED IN ORDER!


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