Solving a physics problem is . .
a. . meant to happen very quickly, as long as you have memorized the correct equation and answer.
b. . a basic "plug-and-chug" process, in which you are given some numbers, you "plug" them into an equation, and an answer is given.
c. . a step-by-step process that takes time, and is essential for learning physics concepts.
d. . an optional activity, not really required in order to understand the physics concepts.

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.)