Names:
Lens Lab
Please put both names on both lab worksheets. Make sure that everyone’s data table and
question section is complete and correct because one will be chosen at random and everyone
in the group will receive the same grade.
Procedure:
1.) Enter the following link into your URL: http://phet.colorado.edu/sims/geometricoptics/geometric-optics_en.html
2.) Explore the site and as you change different variables document your observations and
inferences in the provided data sheet
3.) After your group has completed your data sheet answer the questions below. Keep the
simulation open and use it to answers the question below.
Questions (answer on a separate sheet of paper):
1.) What do the rays (lines) in the simulation represent?
2.) Which ray option(marginal rays, principle rays, or many rays) is the most realistic? Why?
3.) Click the option “2nd Point.” Drag the second point to a different spot on the object. How
does the point where the rays leave the object relate to where they intersect on the
image?
4.) If only the object and lines are provided, how do you know where the image is located,
and how would you be able to determine its orientation?
5.) Describe why light bends when it hits the lens in the simulation. Are they any times
when the light does not bend when it passes through the lens? Why/why not?
6.) If you want to project your image onto a screen. What would happen to the image if the
screen was located at any point besides the point where the rays intersected? (If it
helps, you can alternate between an image and screen by clicking screen)
7.) As shown below the human eye contains a lens. We can see because our pupil allows
light to pass into our eye and through the lens which projects the image onto our retina.
The retina acts like a screen for the image and our optic nerve takes what is projected
onto the screen and transports it to our brain.
What is the orientation of the image of that is projected onto our retina?
8.) Below is a diagram of light entering into an eye.
Does this person see a clear image? Explain.
9.) You are an optometrist (eye doctor) that is going to perform laser surgery on the lens in
the eye above. Using what you learned from you lab, what are all the different ways you
could change the lens to help this person see a clear image?
When you finish follow the link:
http://www.compadre.org/Physlets/optics/illustration36_1.cfm
Explore the different eyes (healthy, farsighted, and nearsighted) and if they are able to see a
clear image from a far source/near source. How can you tell when the eye sees a clear image?
In theory the healthy eye should be able to see an image from both far and near sources, does
is? What do you need to change in order for it to focus the image? What do you think is the
definition of farsighted and near sighted? What are different ways you could fix the problem?
Be prepared to discuss this simulation as a class.