Do Now

• Turn in Web Quests from last class!• Take a clicker and a slip of paper; set

aside• Take a POGIL and complete the ‘WARM

UP’ #1-9

Demo

• Fill out the DO NOW portion of your chart

UV cont.

Is this beautiful? How about this?

UV cont.

A very bad case of skin cancer Localized skin cancer

X-Rays

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

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

X-Rays cont.Over exposure of the hand. This is an x-ray technician’s hand. Over-exposed ankle

Gamma radiation• Gamma Radiation has the shortest wavelength

and the highest frequency in the EM spectrum.

Are wavelength and frequency directly or inversely proportional?

1 2 3

21%

0%

79%1. Directly2. Inversely 3. Not sure

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.

Alpha, beta and gamma penetration Most extreme

POGIL

• Check in at stop signs!

Would you say that high frequency or low frequency EM waves are most dangerous?

1 2 3

86%

0%

14%

1. High2. Low 3. Not sure

Do high frequency EM waves have any benefits?

1 2 3

90%

0%10%

1. Yes2. No 3. Not sure

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

checkpoints??

1 2 3

80%

0%

20%

1. Millimeter wave2. Backscatter X-Ray3. Not sure

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

27.7 Polarization

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.

27.7 Polarization

A vibrating electron emits a polarized electromagnetic wave. • A vertically vibrating electron emits vertically polarized light.• A horizontally vibrating electron emits horizontally polarized light.

27.7 Polarization

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.

27.7 Polarization

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

27.7 Polarization

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

27.8 Polarized 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.

27.8 Polarized 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.

27.8 Polarized Light and 3-D Viewing

Does light travel in a transverse or longitudinal wave?

1 2 3

82%

0%

18%

1. Transverse2. Longitudinal 3. Not sure

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

1 2 3

0% 0%0%

1. A2. B3. C

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.

27.8 Polarized Light and 3-D Viewing

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

1 2 3

6%

88%

6%

1. A2. B3. C

Exit Slip

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

• CLICKERS RETURNED IN ORDER!