Physlet Illustration: Near Point

 

 

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The human eye accommodates for near and far objects by changing its focal length.  This simulation shows the lens, outlined in red, and the retina, drawn in yellow, of an eye that is trying to accommodate by contracting its ciliary muscles (the position is given in millimeters and the angle is given in degrees).  The effect of the cornea has been included in the lens.  What is the near point for this eye?    

Hints:

  1. Drag the object (arrow) back and forth and observe where the image forms.  
  2. Begin with the object far from the lens.  At what object position does the image first form on the retina?

Reference

See Walker, Sections 27-1

Illustration written by Mario Belloni and Chuck Niederriter