Lessons / Activities : Lessons EA-100

Can You See It?

Objective:The student will be able to plot data on a scatter plot graph and interpret the information found there. The student will be able to determine the line of best fit and eliminate incorrect equations. The student will observe the distance between the light source and the light probe which measures intensity.

Engage:Discuss with students the brightness of the city lights at night. Have students describe the purpose of sunglasses. Have students describe the differences in highway roads at night and the city streets at night.

Explore:

1. Students will mark off the sidewalk with colored chalk in 5 ft. increments for a total of 50 ft.
2. The teacher will move a car to the end of the markings( at 0 ft.) and turn on the low beam headlights.
3. Students will begin at the 50 ft. mark and move towards the car in 5 ft. increments until they are able to see that the bulb of the headlights is on. The student will then mark that distance on their data sheets. Each student will perform the activity.
4. After completion, the students will return to the 50 ft. mark and put on their sunglasses and repeat the experiment.
5. Next, the students will remove sunglasses, return to the beginning and the headlights will be increased to high beam.
6. Students will repeat numbers 3 and 4. NOTE: The experiment could be expanded by using different types of sunglasses and comparing the strengths of the shading of the sunglasses.
7. Students will have collected 4 columns of data at the end of the activity.

Explain: Discuss light intensity.
Break students into groups of 4. Each group will be responsible for collecting all data and making scatter plot graphs for each column of data from all members of the class. Scatter plot graphs could be done on transparencies to share with the class as well as overlaid to see any differences and similarities. This would confirm to all students whether they have correctly graphed the data.

Elaborate: Students will perform the following experiment using the EA-100.

Equipment
meter stick
light source with dimmer switch
tape
light probe
wooden block 2" x 4"
EA-100
CFX-9850G+
Light program
classroom table
data communication table




1. Perform the experiment as follows:

   Connect the light probe in CH1 of the EA-100

   Using the data communication cable connect the EA-100 and the CFX-9850G+

   On a long flat surface (classroom table) place a meter stick securely on the table. Use the tape to mark off increments of 5 cm beginning with 30 cm. Label each distance through 100 cm (30, 35, 40, …100).

   Mount the light probe on the block of wood so that it is aligned with the center of the light source.

   Place block at the mark for 30 cm.

   Turn on light

   Retrieve program LIGHT from the CFX-9850G+ Go to Main Menu and select PRGM Cursor down to highlight LIGHT EXE

   Follow screen directions: At "HOW MANY POINTS?" enter 10 At "ENTER DISTANCE" enter 30 At "PUSH TRIGGER" do so Move sensor block to 35 cm and repeat until all 10 data points have been collected

2. Push EXE to display Graph

Evaluate: Students will write and explain the intensity of the light with respect to the distance they are from the light source. Also the students will be able to explain the relationship of the x and y axis and why the data is only in the first quadrant. The students will be given new data and asked to create a new scatterplot graph and draw the line of best fit. Students will discuss the differences in light intensity as respect to sunglass usage and nonusage. For further classroom discussion, the different groups of students could each be given a different wattage of light and asked to plot the data using the same differences. Each group could be given an overhead transparency to plot their data and report it to the rest of the class

Developed by:
Maxine Edwards and Mary Teal
Butler High School Matthews, NC

additional help from:
Neal Farley
Independence High School
Charlotte, NC