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                     Light

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Let there be Light! Light is a particular type of electromagnetic radiation that can be seen and sensed by the human eye. Three things can happen to light when it interacts with an object:
      1. the light may pass through the object if the object is transparent or translucent; 
      2. the light may reflect from the surface of the object; or 
      3. the light may be converted to another form of energy such as heat or converted to
           electrical energy.

 Understanding these three processes will help us understand fundamentals of weather, mirrors, telescopes, and the glasses that your facilitator is wearing.   When considering the absorption of light energy, students tell me they understand the role of color in the conversion of light energy to heat (absorption). They tell me that mom and dad always told them not to wear black colored clothes in the summer because it would make them warmer. This appears to be true, but lets check it out. We will take three soup cans, paint them different colors, allow a strong light to shine on the soup cans, and see which can warms up the fastest and, also, which can cools off the fastest. In order use our time wisely (this experiment takes a bit of time to do), I will provide you the data from an experiment that has already been done. It is your job to record the data, draw a graph from the data, and determine which can warms up the fastest and which can cools off the fastest.
Topic Objective
Demonstrate understanding of the Light topic by mastering the topic objectives, conducting an experiment, applying learning outcomes to related research, stating the relevancy of at least two topic concepts in a written topic report.

Assignment - In General

1.  Read the topic in your textbook.   
2.  Write the Procedure Section of the topic report. The procedure section of the topic report is a summary of what is going to be done for this report. There should be one paragraph for each “part” of the investigation (laboratory). Each paragraph should discuss what is to be done and how it is to be done. 
3.  The Data section of your report.  The Data Section contains the data obtained from the laboratory investigations. The data is presented using the electronic data sheets obtained from the web site. Post any questions you have to the Discussion Board.
4.  Write the Outcomes section of the topic report. The Outcomes section of the topic report presents the specific outcomes for each part of the laboratory activities with respect to the research questions. There should be one paragraph for each “part” of the investigation (laboratory).
5.  Write the Application section of the topic report. The application section of each seminar identifies an activity or activities that involved the web.

Each application includes: 1) A picture that identifies the web site. The picture must include URL and Part of Page as ONE Picture. 2) A description the contents of the web site or activity. 3) An indication on how the web site applies to the topic. 

         
 

Visit the site listed below.

http://www.phy.ntnu.edu.tw/~hwang/fishEye/fishEye.html

(JA- The world above the water surface" viewed from fish’s eyes) 

           
6. The Relevancy section of your topic report: 
     a. Identifies and lists a minimum of two concepts presented in this topic. 
     b. Discusses and relates each concept to your life.
7. Write the "Summary" section of your report. The Summary section summarizes the work of the topic. This should include a broad statement of outcome of the the topic, thoughts, based upon the work of this topic including feelings about the content of the topic and how the topic relates to your life.  Also, post this section of your report to the Discussion Board.
8. Take the on-line topic quiz and include your final set of answers in your topic report. Any questions you are uncertain of the answer post to the Discussion Board.
9. Online students submit your topic report, to the Email address assigned by your instructor, before the assigned deadline.
 
Specific Assignment for On Line Students
    Overview  
      This topic, on Light,  will be using simulators instead of actual laboratory equipment. Since approach is different from what you have done thus far in the course I want to provide specific examples and directions to clarify your work.

The graph for part A will be completed using the data provided. A simulator will be used too complete parts B- reflection and C- refraction. The simulator will be set-up to match the laboratory experiment indicated in the textbook. Upon setting up the simulator correctly a picture will be obtained using IrfanView. The picture(s)  will replace the corresponding picture/drawing in the data sheet. Any questions pertaining to the data, listed in the data sheet, would be answered.
 

 
    Assignment  
1. Read the topic in your textbook.   
2. Write the Procedure Section of the topic report. The procedure section of the topic report is a summary of what is going to be done for this report. There should be one paragraph for each “part” of the investigation (laboratory). Each paragraph should discuss what is to be done and how it is to be done. 
3. The Data section of your report.  The Data Section contains the data obtained from the laboratory investigations. The data is presented using the electronic data sheets obtained from the web site. Post any questions you have to the Discussion Board.
Part A- Absorption:  How does the surface affect the absorption of light energy?
Using the data provided for the absorption of light experiment. Graph the data, analyze the graph and answer al questions in the data sheet.

 

Light On (min.)

Light Off (min.)

0

3

6

9

12

15

18

21

24

27

30

33

36

White °C

25.0

25.8

26.5

27.2

27.9

28.2

28.7

28.3

27.6

26.9

26.3

25.7

25.4

Gray °C

25.0

25.9

27.1

28.1

29.0

29.8

30.2

29.3

28.5

27.5

26.9

26.2

25.2

Black °C

25.0

26.9

27.2

28.2

31.2

31.2

32.4

31.2

30.0

28.1

26.9

25.9

25.0

 

The simulator is:  Optics Laboratory  

Using the simulator is like using any tool. It will take an understanding of the procedures and a bit of practice. This small  investment of time and energy will make you successful. Soon you will be able to simulate many situations involving reflection and refraction. 

  Part B-Reflection:
Section 1 - Problem: How is light reflected from a smooth surface?  
    Open the Optics Laboratory by clicking on the hot link provided. 

 Click on "Source" then click on the screen and a small box with several beams of light will appear on the screen.  Select the "Source" by clicking on it.

 
    By clicking on the dot and dragging the dot the number of rays can be selected. Select or create one ray. Adjust your ray so that it strikes the intersection of the yellow line (normal) and the spot where you will place the mirror (Blue line).  
    Create several more rays of light. Each ray will be striking the mirror at a different angle.  
 

Click on "mirror" then click on the screen, of the Optics Laboratory, and  a mirror will be inserted onto the screen. Click on the mirror and the mirror will become active (little dots/handles appear). Click on one of the dots and drag it toward the center line until a plane, flat, mirror is produced. Please note f1 is the focal length in centimeters and x represents the position of the cursor.

Observe the angle created between the normal and the incoming ray called the angle of incidence. Observe the angle created between the normal and the reflected ray called the angle of reflection. Compare the angle of incidence and the angle of reflection for each incoming ray of light.


Use IrfanView to paste a picture, representing the various angles, into your report to explain the "Law of Reflection".  You may have one picture with several angles or several pictures each with a different angle.

 
Section 2 - Problem: How is light reflected from a curved surface?
Concave Mirror
  Place four "Sources" each adjusted to make one ray, as indicated, to produce the incoming rays.
  Place a mirror on the simulator. Adjust the mirror to produce a focal length of 4.5-cm. (Drag the small white dots associated with the mirror). Your drawing now has the reflected rays.
  Using IrfanView take a picture and paste it into your report. Once the picture is in the report use the drawing toolbar to add normal rays to your drawing.
  To draw the normal lines two small bits of geometry would be useful.
First
- the center of the circle is twice the focal length. The center of the circle/concave mirror would be  2 x 4.5-cm or 9.0-cm. (See yellow dot).
Second - a line drawn from the center of circle to the circle, at the point the light ray touches, is perpendicular at that point and is therefore a normal. (See yellow line)
  Place a dot at the center of your circle/curved mirror and draw a normal for each ray of light. Compare the incoming angle and reflected angle.
Notice there will be four incoming rays, four reflected rays, and four normals in your finished picture.

Convex Mirror
  Using the "Source" place four rays as indicated to produce the four incoming  incoming rays.
 
Place a mirror and adjust it to produce a focal length of -4.5-cm. this will create four reflected rays.
  Using IrfanView take a picture and paste it into your report. Once the picture is in the report use the drawing toolbar to add normal rays to your drawing.
  To draw the normal rays  place a dot on the opposite side of the mirror indicating the center.  (See yellow dot) Draw normal lines from the center to the mirror and continue through the mirror and continue as far as the "source" boxes. (See yellow line) Compare the incoming angle and reflected angle.
Notice there will be four incoming rays, four reflected rays, and four normals in your finished picture.
Part C-Refraction: 
Section 1 - Problem: What is refraction?  
      Visit the indicated web site on refraction.
    

      http://micro.magnet.fsu.edu/primer/java/scienceopticsu/refraction/index.html

                                                      Refraction

 
     

Use the simulation to understand the "Law of Refraction" and use your understanding to indicate how a ray of light is bent as it passes from the air through an piece of plastic and back into the air as indicated in part C.  Using IrfanView take a picture of the simulator and paste it into your report keeping the existing drawing on the data sheet Use the drawing toolbar and add incoming, refracted, and normal rays to the drawing, provided on your data sheet, based upon the the "Law of Refraction".
Your final drawing should include the incoming, refracted, and normal rays entering a more dense optical material (plastic) and include the incoming, refracted, and normal rays entering a less dense optical medium (air).   

 

 
 
         
Section 2 - Problem: How does a double convex lens affect light?  
Using the Optics Simulator insert a convex lens with a focal length of 15-cm  (drag dots/handles to obtain correct focal lengths) into the simulator. Using IrfanView take a picture and paste it into your report replacing existing picture. Use the drawing toolbar to add any lines to support your data.
Section 3 - Problem: How does a double concave lens affect light? 
Insert an concave lens with a focal length of -15-cm  (drag dots/handles to obtain correct focal lengths) into the simulator. Using IrfanView take a picture and paste it into your report replacing existing picture. Use the drawing toolbar to add any lines to support your data.
Section 4 - Problem: How does a telescope work?
Insert an objective convex lens with a focal length of 40-50-cm focal length and an eyepiece with a focal length of 15-cm. (drag dots/handles to obtain correct focal lengths) into the simulator. Using IrfanView take a picture and paste it into your report replacing existing picture. Use the drawing toolbar to add any lines to support your data.
 

Please remember to answer all questions included in your laboratory data sheets.

 

Additional References

 http://micro.magnet.fsu.edu/primer/java/scienceopticsu/reflection/index.html

Angles of Reflection

http://www.glenbrook.k12.il.us/gbssci/phys/Class/refln/u13l3b.html

Concave Mirrors

http://www.glenbrook.k12.il.us/gbssci/phys/Class/refln/u13l4a.html

Convex Mirrors

http://www.explorescience.com/activities/Activity_page.cfm?ActivityID=51

Prism and Spectrum

http://www.explorescience.com/activities/Activity_page.cfm?ActivityID=52

Converging Lens

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/magnify/index.html

Refraction With A Double Convex Lens

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/microscopy/simplemagnification/index.html 

Simple Magnification

4. Write the Outcomes section of the topic report. The Outcomes section of the topic report presents the specific outcomes for each part of the laboratory activities with respect to the research questions. There should be one paragraph for each “part” of the investigation (laboratory).
5. Write the Application section of the topic report. The application section of each seminar identifies an activity or activities that involved the web.

Each application includes: 1)A picture that identifies the web site. The picture must include URL and Part of Page as ONE Picture. 2) A description the contents of the web site or activity. 3) An indication on how the web site applies to the topic. 

         
 

Visit the site listed below.

         
         

http://www.phy.ntnu.edu.tw/~hwang/fishEye/fishEye.html

(JA- The world above the water surface" viewed from fish’s eyes) 

6. The Relevancy section of your topic report: 
     a. Identifies and lists a minimum of two concepts presented in this topic. 
     b. Discusses and relates each concept to your life.
7. Write the "Summary" section of your report. The Summary section summarizes the work of the topic. This should include a broad statement of outcome of the the topic, thoughts, based upon the work of this topic including feelings about the content of the topic and how the topic relates to your life.  Also, post this section of your report to the Discussion Board.
8. Take the on-line topic quiz and include your final set of answers in your topic report. Any questions you are uncertain of the answer post to the Discussion Board.
9. Online students submit your topic report, to the Email address assigned by your instructor, before the assigned deadline.
10. Return all equipment to its original package. Make sure that the materials are neat and clean, ready for the next student. Remember part of your grade is dependent upon proper handling of the equipment.

 

"Nothing in life is to be feared. It is only to be understood."
Marie Curie

Last Updated: Wednesday, March 18, 2020