## GBS Physics Resources

The Physics Classroom

# Henderson's Physics 163

### Chapter 16 Opening Questions

Tuesday, April 15:

A light source is placed 10 cm from a surface. A student measures an illuminance of 48 units. What illuminance would be measured if the same light is placed ...
a. ... 20 cm from the surface?

b. ... 30 cm from the surface?

c. ... 40 cm from the surface?

Wednesday, April 16:

Two lights are arranged above a white sheet of paper. When the lights are turned on they illuminate the entire sheet of paper (as seen in the diagram at the right). Each light bulb emits a primary color of light - red (R), green (G), and blue (B). Depending on which primary color of light is used, the paper will appear a different color. Express your understanding of color addition by determining the color which the sheet of paper will appear in the diagrams below.

Thursday, April 17:

White light (red-green-blue) is shown incident on a sheet of paper which is painted with a pigment which absorbs one of the primary colors of light. For each diagram, indicate which color(s) of light are absorbed, which color(s) of light are reflected.

Friday, April 18:

Opaque objects imparted with pigments selectively absorb light and reflect whatever light colors are not absorbed. Filters are transparent materials which selectively absorb (or block) one or more primary colors of light and allow the remaining colors of light to pass through (or be transmitted). The color of the filter describes which color of light is transmitted by the filter. The following diagrams depict various primary colors of light (R for red, B for blue, and G for green) incident upon a colored filter (C for cyan, M for magenta, and Y for yellow). Determine which primary colors of light will pass through the filters.

Monday, April 21:

Consider the diagram shown below. How do the polarized side windows in these adjacent houses provide privacy for the occupants? Who can see what? Explain.

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