PASCO OS-8459 Beginning Optics System - Manual (Page 43)

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M o d e l N o . O S - 8 4 5 9 T e a c h e r ’ s G u i d e
43
Teacher’s Guide
Experiment 1: Color Addition
Note on procedure: Student’s expectation may differ from actual results. Encourage them to carefully
observe the resulting colors and describe them accurately.
Part 1, typical results:
Part 1, answers to questions: 1. Mixing light is not the same as mixing paint. The mixing of colored light
is additive mixing; the mixing of paint is subtractive mixing. 2. In this experiment the mixture of red, green, and
blue does not look pure white to most people. To produce white light, the three colors must be present in a spe-
cific ratios of intensities.
Part 2, typical results:
(Step 4) Under red light, black ink is easier to see than red; red ink appears nearly the same color as white paper.
Part 2: answers to questions: 1. Red ink appears red because it reflects red light and absorbs other colors.
Under blue light, red ink absorbs most of the visible light. 2. Under red light, red ink is difficult to see because
both ink and paper reflect most of the visible light.
Experiment 2: Prism
Notes on procedure: (Step 3) (a) Red, Orange, Yellow, Green and Blue are seen in that order. (b) Blue is
refracted at the largest angle.(c) Blue is predicted to refract at the largest angle because its index of refraction is
largest. (Step 4) When colored rays enter the prism, they do not emerge parallel to each other because of their
differing indices of refraction.
Table 1.1: Results of Colored Light Addition
Colors Added Resulting Color
red + blue + green slightly bluish-white
red + blue pink-purple
red + green yellow-orange
green + blue bluish-green
Table 1.2: Colored Ink Observed Under Colored Light
Color of Light Line Apparent Color of Ink Do they look different? Actual Color of Ink
Blue Light
A Black
Yes, slightly
Red
B Black Black
Red Light
C Black
Yes, slightly
Blue
D Black Black