Materials Needed s1

Tilt Lab

Materials Needed

 Plastic shoe box  Flashlight  Masking tape  Piece of graph paper  5 different colors of markers or colored pencils  Ruler  Protractor  Lab sheet

Preparing the Light Source

1. Place the plastic shoe box on a table, or on the flat, firm floor. 2. Lay the flashlight on its side on top of the plastic shoe box and line up the edge of the flashlight so it is close to the edge of the stepping stool, brick, or block. Use masking tape to tape the flashlight down so it can't roll around.

3. Hook a piece of graph paper an a small white board and place vertically in front of the flashlight. Move the white board 3-4 inches away from the flashlight, until the light on the paper forms a medium-sized, sharp circle 2–3 inches in diameter. Put a piece of tape in front of the box and a piece of tape in front of the white board so you can keep the graph paper at this starting distance for all testing. Write down this starting distance on your lab sheet. Testing the Surface

1. Have a helper hold the graph paper vertically (90 degree angle from the floor) at the starting distance in front of the flashlight. 2. Use one color of marker or colored pencil to draw around the outline of the light on the graph paper. Be sure to mark on your lab sheet which color is for which angle. The graph paper is at 0 degrees tilt for this outline. 3. Observe the brightness of the light inside this outline and record your observation on your lab sheet. 4. Place the protractor next to the graph paper, at the spot shown in Figure 3, and tilt the graph paper 10 degrees away from the flashlight (tip the white board from the 90-degree mark to the 100-degree mark). 5. Use a different color to draw around the outline of the light on the same piece of graph paper. Again, be sure to mark on your lab sheet which color is for which angle. The graph paper is at 10 degrees tilt for this outline. 6. Observe the brightness of the light inside this outline, and record your observation on your lab sheet. Compare the brightness to the previous outline. 7. Repeat steps 4–6 for tilt angles of 20, 30, and 40 degrees.

Analyzing the Graph Paper

1. For each sheet of graph paper, count the approximate number of squares inside each light outline – either fully enclosed or at least half enclosed. Enter your counts in the data table on your lab sheet.

2. Get the information from two other groups and put on your lab sheet. 3. Calculate the average number of squares inside each outline for each degree of tilt and enter your calculations in the data table. 4. Plot the degree of tilt on the x-axis and the average number of squares illuminated on the y-axis. You can make a line graph. Tilt Lab Sheet

Problem: How do the Sun’s light rays strike a flat surface at different angles? (similar to investigation on Pages 44-47 of Planetary Forecaster)

Background:

Direct light –

Indirect light -

Data Table: Number of Lighted Squares

Degree of Tilt Color Your Graph Paper Graph Paper 2 Graph Paper 3 Avg. Number 0 10 20 30 40

Degree of Tilt Brightness of Light

Attach your own piece of graph paper with your graph of the results. Analysis Questions: please write in complete sentences

1. How did the numbers of squares inside the outline change as the angle of the surface it strikes changes?

2. How did the brightness change as the angle is increased?

3. What is the relationship between the angle at which the light strikes and the area covered by light? For example “As the angle increases, the area ______.”

4. How do the words indirect and direct relate to this investigation?

5. Based on your results, what do you think happens to the intensity of light from the Sun as you move away from the Equator? Is the light more direct or less direct?

6. As light becomes less direct, what do you think happens to the temperature in those areas?

Extension: Design an experiment that would Test question #6.