Solving Physics Lab Report Questions

AI Thread Summary
The discussion revolves around two physics lab report questions related to optics. For the first question, the user is trying to determine the focal length of a projection lens needed to project a 12 ft wide image from a 1-inch wide film at a distance of 50 ft. The user is uncertain about the correct values for object distance (u) and image distance (v) in the lens formula. In the second question, the user is calculating the focal lengths of the objective and eyepiece lenses of a 24-inch long telescope with a magnifying power of 15, but is unclear on how to incorporate all parameters into the calculation. The user seeks clarification on these concepts to complete the lab report.
SpatialVacancy
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Hello,

I have just finished what seems like an infinite amount of questions for this lab report. 2 of them I am just not sure how to proceed. Any help would be appreciated.

Question 1:
In a film projection apparatus, it is desired to produce pictures 12 ft wide on a screen 50 ft from the lens. The size of the picture on the film is 1 in. wide. What must be the focal length of the projection lens used?

Question 2:
The magnifying power of an astronomical telescope 24 in. long is equal to 15. Determine the focal length of the objective lens and that of the eyepiece. Assume the telescope is focused on a distant object.

Thank you.
 
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1) Because 1/u + 1/v = 1/f, from what I understand u = 50ft and v = 1 inch (Could be wrong..)

2) Guessing here, but Power of lens = 1/focal length, thus 15 = 1/f, 15f = 1, f = 1/15
 
Im not sure that is right. How does it take into consideration the other parameters of the problem?
 
That's exactly where my uncertainty comes from..
I'll have to get back to you on this one.
 

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