People who do very detailed work close up, such as jewelers, often can see objects clearly at a much closer distance than the normal 25.0 cm. Required:
a. What is the power of the eyes of a woman who can see an object clearly at a distance of only 7.25 cm?
b. What is the size of the image of a 2.00 mm object, such as lettering inside a ring, held at this distance?
c. What would the size of the image be if the object were held at the normal 25.0 cm?

Certain bacteria (such as aquaspirillum magnetotacticum) tend to swim toward the earth’s geographic north pole because they contain tiny particles, called magnetosomes, that are sensitive to a magnetic field. if a transmission line carrying 100 a is laid underwater, at what range of distances would the magnetic field from this line be great enough to interfere with the migration of these bacteria? (assume that a field less than 5% of the earth’s field would have little effect on the bacteria. take the earth’s field to be 5.0 * 10-5 t, and ignore the effects of the seawater.)