When an external magnetic field is applied to a material, these current loops tend to align in such a way as to oppose the applied field. This causes all materials to be repelled by a permanent magnet; however, the resulting force is usually too weak to be noticeable.
Sources of E. coli. E. coli O157:H7 is most commonly found in cows, although chickens, deer, sheep, and pigs have also been known to carry it. Meat becomes contaminated during slaughter, when infected animal intestines or feces come in contact with the carcass.
Different strains of E. coli can be found in different type of animals, so we can determine the source (from human or from other animals) of the stools by examining which strain of E. coli is present in the stools. E. coli can also be found in environments at higher temperature, such as on the edge of hot springs.