Don\'t quite get questions 1-6 For lenses in combination, the image for the firs

Question

Don't quite get questions 1-6

For lenses in combination, the image for the first lens is the object for the second. The ray tracing diagram below shows how the rays travel through the system from object to first image/second object and then to second image. The first ray trace gives the location and size of the first image. A second ray trace is performed to find where the second object (which is the first image) creates the second image. It is possible for the images and second object to be virtual. In our drawing all objects and images are real. Remember that the distances are measure with respect to the particular lens in question! When solving this using the thin lens equation, the first image distance is how far it is from the first (i.e. left) lens. The second object distance is where the first image is relative to the second (i.e. right) lens. The following equations hold: 1/d_1, 0 + 1/d_1, 1 = 1/f_1 1/d_2, 0 + 1/d_2, 1 = 1/f_2 Make sure you apply these appropriately! Since you know the focal length of each lens, calculate the location of where both lenses need to be in order to make an image on the screen when the screen is far from the object. This may require some trial and error on your part. Prior to attempting this, answer the following questions. Which lens should go closer to the object, the shorter or longer focal length? What difference does it make? How do you calculate the magnification? Place your lenses in position. Insert the screen where you expect the first image to appear. Is it there? If not revisit your calculations. Measure all distances and image sizes. Verify that each lens obeys the thin lens equation and your final object has the magnification you expect.

Explanation / Answer

as both lens are of converging lens type,

if object is placed in between focus point and lens , the image formed is virtual

which is not desired in this scenario.

so the shorter focal length lens should be closer to the object

so that the you have more independence to move the object nearer to the lens without risking the image formed to be a virtual one.

Q2. total magnification=magnification of first lens*magnification of second lens

magnification of any lens=distance of image/distance of object

Q3. to be done in your lab.

Q4. calculate the object distance.

the focal length is known.

using thin lens equation, calculate the image distance.

place the screen at the distance calculated.

Q5. to be done by you in the lab.

Q6. use the thin lens equation and the object and image distance recorded by you

and then check that the thin lens equation is indeed obeyed

there might be a small variation owing to error in measurements but there should not be bigger variations

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