Examine the distant stars and nebulae

Question

Assignment:

Answer the following questions. Explain your arguments.

1. An amateur astronomer has a telescope to examine distant stars and nebulae. The focal length of the main objective lens of the telescope is f= 710 mm. At what distance from the lens will a distant star be imaged using this objective lens? Give your answer in units of metres.

2. The human eye has a nominal lens to retina distance of S_i= 1.7 cm = 0.017 m . What does the focal length of the lens in the eye need to have if the Object to lens distance (S_o) is:

a) S_o = 15 cm= 0.15 m

b) S_o = 1m

c) S_o = 15 m

d) S_o = 100000 km = 10⁸ m

The human eye has an internal lens component that it can flex to change the effective cornea/ lens focal length. Using the results from parts a) through h) what is the percent change in focal length over the wide distances seen by the eye from very close to very far? Explain.

3. A cell phone has a fixed focal length lens of f = 3.85 mm = 0.00385 m and can take pictures over a range of distances from S_o = 0.5 m to S_o = infinity. Over what range of distances (S_i) does the lens in the cellphone have to move to focus an image at these two extremes in object distance?

4. A microscope is being used to study cells on a slide. The lens to image distance is S_i in the microscope is S_i = 160 mm = 0.16 m. If a microscope objective of focal length f= 12.5 mm = 0.0125m is used, how far is the object to lens distance (S_o).