Question

Each of your eyes has a lens in it. This lens can change its shape and hence its focal length. By changing the focal length you are able to focus on an object based on how far away it is from you. For this problem you will determine the maximum focal length of your eye.

A. To determine the maximum focal length of your eye you need to establish how far you can see under ideal conditions (no fog, an unobstructed line of vision). Bear in mind that how far you can see is not the same as what distance an object is visible at. You may not be able to make out a pen a mile away from you but you can easily make out a mountain at that distance. When it comes to discerning objects, the size of the object matters.

Which of the following objects is the furthest away?

TheMoon

The Sun    

Mars

Halley's Comet

Pluto

Any star (besides the Sun)

State how far away the object is. This will be your object distance.
cm

B. The average human eye has an image distance of 1.7 cm. In other words, it is 1.7 cm from the lens in your eye to the retina. Using this information and your answer to A, determine the maximum focal length of your eye. Also determine the magnification for this situation.
FOCAL LENGTH = cm
MAGNIFICATION =

How do I know what object distance to use?

Answer 1

a) Here we have distance from earth to sun is 149.6 million km Distance from earth to moon is 384400 km Distance fromearth to mars is 401 million km Distance from earth to Halley's Cometis 5.1million km Distance fromearth to Pluto is 4.67 billion km So Pluto is furthest away b) We have from lens equation u V Here we are asked to use the distance from part (a) as the object distanc U V f 4.67x10 1.7x10 f =0.017m Magnification 1.7×10-2 4.67 x10 3.64 x10-5