An open-ended tube is held vertically in a bucket of water so that one end is submerged. At
the upper end a ringing 1000 Hz tuning fork is held. Together the tube and tuning fork are
raised and lowered. When 42.9 cm of the tube is above water a strong sound is heard from
the tuning fork resonating in the tube. The tube and tuning fork are then raised
together. The sound dies out and, at a new height, gets strong again.
a. What is the wavelength of the sound?
b. How far in cm is the tube raised between the two resonances that were found?
c. What two modes have been excited in the tube? Give both the mode number (1st, 2nd,
3rd, etc.) and the integer value m as defined in the textbook.
d. Draw pictures to scale of the tube and the standing wave patterns of the two resonances
found. Label each of the nodes and antinodes with 2 of the following labels: “pressure
node,” “pressure antinode,” “displacement node,” and/or “displacement antinode.”
e. How would the wavelength, frequency, and modes change if this experiment were
conducted in a room full of helium instead of air