Chapter 4: Q18E (page 948)
Certain bacteria (such as Aqua spirillum 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 of the earth’s field would have little effect on the bacteria. Take the earth’s field to be , and ignore the effects of the seawater.)
Short Answer
If the bacteria are within r = 8m of the cable, its magnetic field may be strong enough to affect their sailing.