Do Now: (No longer allowed to borrow textbooks as one went missing last B day)Take a clicker and take back your exit slips. READ page 414-15 and make corrections. Then, take out a textbook and read page 416 FIG 27.20; try that and try the stereogram on p. 417 (FIG 27.22) I also have a Magic Eye book at my desk to borrow. You can try the illusions on p. 418, tooHW :Read and study CH 28, do #1-8Finish POGIL if you don’t during class

Were you able to see the stereogram?

1 2 3

0% 0%0%

1. Yes 2. No 3. Not sure

SHORT WAVELENGTHS interact more frequently than longer wavelengths (when passing through transparent material). What takes more time to get through glass – blue light or red light?

1 2 3 4

63%

0%0%

38%

1. Blue 2. Red3. Same 4. Not sure

A light wave incident upon a pane of glass sets up vibrations in the atoms. Because of the time delay between absorptions and reemissions, the average speed of light in glass is less than c.

c stands for ‘speed of light’

27.4 Light and Transparent Materials

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.

However, light that is ‘glancing’ (glare from road, water, etc) IS polarized. Additionally, light that passes though a polarizing lens/filter IS polarized.

27.7 Polarization

When light shines on a polarizing filter, the light that is transmitted is polarized. The filter is said to have a polarization axis that is in the direction of the vibrations of the polarized light wave.

Light passes through two polarizing filters when the polarization axes are aligned (parallel) but not when they are crossed at right angles (90 degrees, perpendicular).

27.7 Polarization

If POLARIZED light tries to pass through a filter…

You have 10-15 minutes to…

• Check in regarding your Ch 27 POGILS if needed (ask questions if you are confused!)

• Review all of the questions at the end of CH 27– HW questions assigned– 24, 28, 31, 32, 34, 35, 36 (most of these questions

were in your POGILs)• Then, open notes quiz on CH 27

QUIZ – OPEN NOTES• No talking. Talking = forfeit of extra credit and possible

points• Upside down in basket when done• Take a POGIL and SILENTLY go back to your test seats and

start• CELL PHONES/ iPODS on desk where we can see them.• Sit up straight, hands on desks – no cheating • Keep in mind – this is a QUIZ and only has a few

questions on it. You WILL have more quizzes, and you WILL have an open notes QUEST on Ch 27, 28, and anything else we cover before finals. If you did not see a certain topic on this quiz, you WILL see it on the quest and/ or on future quizzes

Ch 28 – COLOR

• In your notes: write WHAT YOU SEE HAPPENING and WHY YOU THINK it is happening