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Light and Optics

Investigation 5 – Lab

Back to Investigation 5

BE PREPARED

Supplies and Equipment:

Group Materials:

5 100 ml beakers
yellow food coloring
water
1 one-liter graduated cylinder 1 pitcher
1 glass stir rod

Group Materials:

1 flashlight
1 metric ruler
1 set of colored filters
1 sheet of unlined white paper 1 black gram cube
1 red gram cube
1 blue gram cube
1 light green gram cube
1 white gram cube

Individual Materials:

1 Student Data Record

Teacher Preparation:

1. Measure 300 ml of water using the graduated cylinder and pour into the pitcher.

2. Add 30 drops of food coloring and stir using the stir rod until it is completely dispersed.

3. Pour approximately 50 ml of the solution into one 100 ml beaker for each group.

4. Place the materials at a central location.

5. Divide the class into five cooperative groups.

Instruction:

1. Ask one student from each group to obtain: one (1) 100 ml beaker containing the yellow colored water, one (1) flashlight, one (1) metric ruler, one (1) set of colored filters, one (1) sheet of unlined white paper, one (1) black gram cube, one (1) red gram cube, one (1) blue gram, cube, one (1) light green gram cube and one (1) white gram cube.

GET FOCUSED

Investigation Five introduces students to light waves and wavelength. In addition, absorption and transmission of light through filters and colored water are explored.

INVESTIGATE

Trial 1

In this Trial, students will demonstrate how colored filters are able to transmit specific wavelengths of the Visible Spectrum while at the same time absorbing other, specific wavelengths. This Trial essentially repeats Trial 1 from Investigation 4 to provide the perspective needed for the following Trials. In conducting this Trial, students will answer the following question:

What is the relationship between absorption and transmission of the wavelengths of the Visible Spectrum?

2. Ask students to follow the procedure in Trial 1 in their Student Data Record.

3. Students should record their observations in the Table in Problem 2b in their Student Data Record.

4. Ask students to answer Problems 2d through 2f in their Student Data Record.

Trial 2

5. In this Trial, students will analyze how white light is transmitted through a colored solution of water and food coloring. This Trial allows students to generalize that in addition to colored filters, other colored and transparent objects are able to transmit specific wavelengths of light. It also serves to prepare students for Trial 3 in which they investigate their perception of the color of the solution.

How does the color of a transparent object affect the color of the light that is transmitted?

6. Ask students to follow the procedure in Trial 2 in their Student Data Record.

7. One student should position the flashlight in the center of the lab table and shine it toward the ceiling.

8. Another student should carefully place the beaker of yellow water on top of the flashlight and hold it in place.

9. A third student should hold the sheet of paper 15 cm above the beaker.

10. Ask students to answer Problems 3a and 3b in their Student Data Record.

11. Students should answer the questions in Problem 3d in their Student Data Record by referring to the diagram of the Visible Spectrum in their Student Data Record.

Trial 3

12. In this Trial, students will analyze how wavelengths of the Visible Spectrum are perceived. Any wavelengths of light not absorbed by the colored solution are transmitted into an observer’s eyes. The perceived color is the color that corresponds to the transmitted wavelengths. In conducting the Trial, students will consider the following question:

How do we perceive the colors of transparent objects?

13. Ask students to follow the procedure in Trial 3 in their Student Data Record.

14. Students should record their observations in Problems 5a through 5d in their Student Data Record.

Trial 4

15. In this Trial, students will analyze how the light of the Visible Spectrum is perceived by observing the colors of solid, opaque objects. This Trial furthers students’ understanding of the perception of visible light by allowing students to generalize their understanding to include solid objects. Any wavelengths of light not absorbed by a solid, opaque object are reflected off of the object into an observer’s eyes. The perceived color is the color that corresponds to the reflected wavelengths. In conducting this Trial, students will consider the following question:

How do we perceive the colors of opaque objects?

16. Ask students to follow the procedure in Trial 4 in their Student Data Record.

17. Students should record their observations of the cubes in the Table in Problem 6a and then answer Problem 6b in their Student Data Record.

18. Students should then use the colored filters to view the cubes. Students should record their observations in the Table in Problem 6e and answer Problem 6f in their Scientist Data Record.

19. Students should answer Problems 6g through 6h in their Student Data Record.

20. On completion of the Investigation, allow sufficient time to return all materials to the correct location in the Lab for storage.