The shortest air column inside a resonator vibrates with a frequency of 250 hz, if the next harmonic is 750 hz, and the speed of sound is 343 m/s.
a. is this resonator closed at one end or open at both ends? explain.
b. find the length of the resonator.

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.)