1. The opening picture for the chapter shows an optical illusion which makes a pencil in a water glass appear broken. Explain how the illusion is caused.
2. Based on the discussion in the chapter, would you expect an astronaut on the space station to see the stars "twinkle"? Explain.
3. What optical effect causes nearsightedness? Explain. What kind of lens is used to correct nearsightedness, and why does this work?