Resonance/Standing Waves on String

PHY 100 & 103

Students will adjust the tension on a vibrating string to change the number of nodes on a standing wave. The masses used on the string to apply the tension force are 55g for 7 segments, 75g for 6, 105g for 5 and 170g for 4.

Equipment

Notes

***There are two versions of this setup. Ask instructor or supervisor which should be used.*** Remove the rods from all thew table clamps and place them in the back. Move the table clamp up towards the top of the table (away from the chairs) but keep it on the same side. Mount a pulley to this clamp. If the pulleys are problematic, the strings may be draped under the pulleys instead of on top. Alternatively, any horizontal rod raised to the same height may be substituted. Put the other table clamp on the other side of the table near the wall and make sure the two clamps are inline.

Use the wax coated string. Make sure the string is long enough to span both clamps and that it hangs down from the pulley half way to the floor. Don't forget to hang a weight hanger from the bottom of each string. Make sure it doesn't touch the floor.

Test each of the apparatuses to ensure that each set of mass yields the corresponding number of wave segments (see description). Adjust by a few grams as needed. If the correct number of segments can't be produced or if there is too much play/slop in the string, tighten the pulley and try again.

For the music class, use the new vibrators with the black function generators. Have them set to 90 Hz and max amplitude (or a little less if the wave gets distorted). For the other classes, use the old vibrators and put them as far down in the clamp as they can go to ensure that 7 segments can be obtained with 55g. Along with the initial apparatus set-up, supply a sufficient number of the appropriate paper procedure handouts for all of the lab sections that will use the set-up over the course of the week. Print the PDF, duplicate to double-sided pages, staple, and leave pile on instructor's table prior to first use of set-up.