1. In the section on the Physiology of the Eye it was stated that “The cornea is responsible for the majority of the ‘focusing power’ of the eye.”  Explain  this statement.  After all, isn’t the majority of the focusing in the eye managed by the eye’s lens?

2. A “crystal ball” is made up a material having an index of refraction of 1.47.  The radius of the ball is 8.0 cm.  What is the effective focal length of this ball if  objects are viewed through it? (Note that this ball is certainly not a thin lens, so the thin lens equation will not hold when trying to relate object and image distances....)

3. What would be the focal length of the ball in the previous question if it were placed in water (n = 1.33)?

4. Why can you not see as clearly when swimming underwater without a mask as you can when you are above the water? (Assume that you do not wear corrective lenses that you take out when you go swimming!)

5. Your friend thinks that her brother needs glasses, but he claims that he doesn’t. While over visiting one time, you ask him to hold out his arm in front of him and see if he can clearly see his raised index finger, including the little hairs on the back of it. He says that he can. You then ask if anything in the room appears just slightly blurry.  He says that he thinks that maybe the picture on the TV seems a bit fuzzy to him sometimes.  You estimate that the TV is about 3.5 m from where he sits when he watches it.  (a) Do you think your friend’s brother needs glasses? Why or why not?  (b) Is her brother hyperopic or myopic? Why?   (c) Approximately what prescription eyeglasses should her brother be wearing?

6. Your mother does not want to admit it, but she really is getting older (aren’t we all...?). She has always prided herself on her excellent eyesight, but you’ve noticed that she tends to hold her book further away from her when she is reading than she used to. You realize that her eyesight is still pretty good, but that she could use some reading glasses to help her see things close up.  You know that stores like K-Mart have simple reading glasses that are pretty cheap, and you have decided that you would like to surprise your mother with a gift of a pair of these glasses to help her read (which she loves to do).  You watch her closely while she’s reading one day, and notice that she moves her book to a distance of about 40 cm from her eye when she is reading. (a) Is your mother myopic or hyperopic?  Why?  (b) What dioptric power eyeglasses should you look for in the store when shopping for a pair of reading glasses for her?

7. A compound microscope has an eyepiece of focal length 8.00 cm and a 4.00-cm objective lens.  The two lenses are separated by a distance of 25.0 cm.  Find and  describe the final image viewed in the eyepiece of an object which is placed 5.20 cm from the objective lens.