PhysicsLAB Lab
Ray Diagrams for Converging Lenses

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In this lab, you will construct the SIX special ray diagrams for converging lenses. In each diagram, an upward arrow has been provided as the object. Label it with an O. For your convenience, blank diagrams will objects already provided are located on this page -- in IE use landscape mode with margins of 0.5. Each case will use the three rays outlined in the resource lesson on converging lenses where you are provided with an animated gif to show you how the image is formed. First watch each animation, then draw your own diagram. Keep your three rays color-coded - that is, let ray #1 be the same color in each diagram, similarly with ray #2 and ray #3. When all three rays come together they locate your image. Draw the image in and label it with a capital I. You are then to measure, in centimeters, do, di, O and I to the nearest 10th of a centimeter.
 
Another source of information is this optics physlet. You can place the "object" wherever you like and observe the formation and properties of its image.
 
Remember that
  • do represents the distance from the object to the lens when measured along the axis of the lens.
  • di represents the distance from the image to the lens when measured along the axis of the lens.
  • O is the height of the object (measured from tip to base - this should be close to 1.0 cm)
  • I is the height of the image (measured from tip to base)
 
An example is shown below.
 
 
The magnification of a lens is equivalently defined as either of the following ratios: M = | I/O | or M = | di/do |. You will be using them to evaluate the precision of your diagrams.
 
Your diagrams will be graded on neatness, so be careful. Remember your arrows!
 
 
Case I: the object is located infinitely far away
 
Refer to the following information for the next five questions.

The image is formed on the line between region ____ and ____.
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
The purpose of this construction is to locate the ____ which defines the focal length of the lens.
 

 
 
Case II: the object is located in Region I
 
Refer to the following information for the next four questions.

The image is formed in region ____.
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
Using the results of your diagram, measure each of the following four distances. Then calculate each magnification and the percent difference between their values.

measurements (cm)
O =
do =
di =
I =

magnification comparisons
M = |di/do|
M = |I/O|
% difference =
 
 
Case III: the object is located exactly two focal lengths in front of the lens
 
Refer to the following information for the next four questions.

The image is formed on the line between region ____ and ____.
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
Using the results of your diagram, measure each of the following four distances. Then calculate each magnification and the percent difference between their values.

measurements (cm)
O =
do =
di =
I =

magnification comparisons
M = |di/do|
M = |I/O|
% difference =
 
 
Case IV: the object is located in Region II
 
Refer to the following information for the next four questions.

The image is formed in region ____.
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
Using the results of your diagram, measure each of the following four distances. Then calculate each magnification and the percent difference between their values.

measurements (cm)
O =
do =
di =
I =

magnification comparisons
M = |di/do|
M = |I/O|
% difference =
 
 
Case V: the object is located exactly one focal length in front of the lens
 
Refer to the following information for the next two questions.

 
Choose the correct property. This image is
 
because
 
 
 
Case VI: the object is located in Region III
 
Refer to the following information for the next four questions.

 
The image can be formed in region ____, region ____, or region ____.
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
Choose the correct property. This image is
 
Using the results of your diagram, measure each of the following four distances. Then calculate each magnification and the percent difference between their values.

measurements (cm)
O =
do =
di =
I =

magnification comparisons
M = |di/do|
M = |I/O|
% difference =

Teacher Certification: 



This form is to be completed individually at the completion of your lab. Input only your numerical values - the correct units have already been supplied on the form. Make sure that your teacher or his/her designee signs off the Teacher Certification area before posting your final submission.

 
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