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PHYS 355 Optics Mid-Term 2 - Lens Systems & Magnification Questions (Fall 2007), Exams of Optics

The mid-term exam for the PHYS 355: Optics course, held in Fall 2007. The exam covers various topics related to lens systems, including calculating the focal length and position of principal planes, determining which lens faces long-distant objects, minimizing spherical aberration, and understanding magnification. Students are required to use provided lens characteristics and solve problems using given equations.

What you will learn

  • What happens to a collimated light beam passing through a symmetric bi-concave lens immersed in oil?
  • What are the focal lengths and positions of the principal planes for lens A and lens B?
  • What are the magnifying powers and meanings for this telescope?
  • How to minimize spherical aberration in a Keplerian refracting telescope?
  • Which lens should face long-distant objects and why?

Typology: Exams

2019/2020

Uploaded on 06/08/2020

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NAME:
Mid-Term Exam 2 – PHYS 355 - OPTICS
Mendes, Fall 2007, Oct 30, 2007
Start time: 9:30 a.m.,
End time: 10:45 am
Open textbook, notes, homeworks, and quizzes
Calculators allowed; no other electronic device allowed
Where it is appropriate, make sure to provide physical units to your numerical answer
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NAME:

Mid-Term Exam 2 – PHYS 355 - OPTICS

Mendes, Fall 2007, Oct 30, 2007

Start time: 9:30 a.m.,

End time: 10:45 am

Open textbook, notes, homeworks, and quizzes

Calculators allowed; no other electronic device allowed

Where it is appropriate, make sure to provide physical units to your numerical answer

  1. (total = 50 points) You are provided with two spherical lenses (both plano-convex) with the following characteristics:

Lens A:

  • radius of curvature of the curved surface = 20.6 mm
  • glass refractive-index = 1.
  • center thickness = 6.4 mm

Lens B:

  • radius of curvature of the curved surface = 103 mm
  • glass refractive-index = 1.
  • center thickness = 10.1 mm

Your goal is to construct a Keplerian refracting telescope with this pair of lenses:

a) (10 points) Calculate the focal length and position of the principal planes of lens A:

b) (10 points) Calculate the focal length and position of the principal planes of lens B:

c) (5 points) Which lens (A or B) should face long-distant objects (moon, stars, etc).

d) (15 points) As we know, in order to minimize spherical aberration, the flat surface of a spherical lens should typically face the long(er) conjugate. With that in mind: i) sketch the telescope by showing the proper sequence and orientation of the lenses (don’t forget to show which direction the light beam is propagating) and ii) calculate the correct distance between the vertices of the two lenses and show it in your drawing.

e) (5 points) What will be the magnifying power of this telescope? What does it mean?

f) (5 points) Will the image be inverted or erect for this telescope?

  1. (total = 15 points) Consider a symmetric bi-concave lens with both radius of curvature of 52 mm, a central thickness of 3.0 mm, and manufactured from glass (refractive-index of 1.52). This lens is to work completely immersed in an oil tank of refractive-index of 1.82. Under those operating conditions, do you expect a collimated light beam to converge or diverge right after passing through this lens? Clearly justify your answer with a conclusive calculation.

oil

oil