Lenses Image Formation
Initial Publication Date: August 15, 2008
Summary
In this physics lab, students will investigate the different types of images that can be created with convex and concave lenses. They will follow a guided lab in producing images at different distances for a given lens and observing whether the images produced are upright or inverted, smaller or bigger, and virtual or real. Students will sketch the images produced for each case while writing up the above observations in the lab packet. In addition to images produced, the students will investigate what happens to an image when different parts of the lenses are blocked and when different parts of the object are blocked.
CollapseLearning Goals
1st goal (Equipment use): The student will be able to take a lens and object and determine where an image will be produced and how to see it.
2nd goal (image formation): The student will be able to describe what happens to an image's size and orientation when the lens is moved to different distances away from the object.
3rd Goal: The student will be able to describe where different light rays from the object end up in order to create the image for the different lens types.
2nd goal (image formation): The student will be able to describe what happens to an image's size and orientation when the lens is moved to different distances away from the object.
3rd Goal: The student will be able to describe where different light rays from the object end up in order to create the image for the different lens types.
Context for Use
This is appropriate for any physics or physical science course that is studying an introduction to optics. Class size depends on the equipment available. 3-4 students per lab set-up is ideal. This is a lab exercise at the beginning of a lens unit in high school physics. This lesson can be completed in a 50 minute time period. The students should have already covered what light is and how it can travel and be manipulated. This activity can be adapted to higher level physics by adding the math concepts behind it and measuring of image sizes and distances.
Description and Teaching Materials
The material needed are as listed per group of students:
1 concave lens
1 convex lens
light source to act as object (preferably with an arrow shape to best understand image inversion)
cardboard to block parts of lens
notecard for screen
The activity will be introduced after studying how light travels as an introduction to lenses and how they affect light. A short demonstration should be given to the students to see how an image can be introduced on a wall in order to save time in frustration. The students will then go into lab and follow the lab manual for this activity. For closure, the students will place their findings on the board and have a discussion of what was found in the lab. Lab Write-up for Lesson (Microsoft Word 33kB Aug15 08)
1 concave lens
1 convex lens
light source to act as object (preferably with an arrow shape to best understand image inversion)
cardboard to block parts of lens
notecard for screen
The activity will be introduced after studying how light travels as an introduction to lenses and how they affect light. A short demonstration should be given to the students to see how an image can be introduced on a wall in order to save time in frustration. The students will then go into lab and follow the lab manual for this activity. For closure, the students will place their findings on the board and have a discussion of what was found in the lab. Lab Write-up for Lesson (Microsoft Word 33kB Aug15 08)
Teaching Notes and Tips
Show the students the general lab set-up and that an image can be formed on a wall with a convex lens. Also show the students how to look back through a lens to see images for a concave lens.
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Assessment
Monitor the groups as they perform the lab and ask questions about what images are being formed. Ask questions about what happens when the object is partially covered vs. the lens partially covered and their ideas of what they think is causing the effects. The lab manual will also be handed in for credit and checked for student observations and results. A quiz will also be given in a follow-up period to check for individual learning and retention.
Standards
9-12.I.B.1 - scientific experimentation