# Homework Help: Stroboscope and string vibration

1. Jan 31, 2006

### logicbomb

I am a college student, currently in Physics II. Got a simple question. I didnt have time in lab / I forgot to do this part, and the lab report is due tomorrow.

Our lab was on standing waves on a string. Using a string vibrating device, and a hanging mass on the other end to play with the tension. The whole point was to get 4 standing waves (well 2 full waves).

Question is as follows-

What is the appearance of the string is the stroboscope is set to twice the frequency of vibration of string? What about is the stroboscope is set to one half of the frequency of vibration of string?

pretty simple i know, like i said, i just completely forgot to do it when everything was set up, and didnt have enough time to hook it all back up. Thanks for your help, i can see myself coming here on a weekly basis.

2. Jan 31, 2006

### Staff: Mentor

Just draw the string for each case and you should be able to figure it out. Of course, the phase of the strobe light will make a difference in what you see. What phase was specified? Was there a trigger opto for the strobe to give a phase reference to the string, or were you supposed to just vary the strobe frequency around the specified frequency to see what phase looked the best/biggest/prettiest?

3. Feb 1, 2006

### logicbomb

yea we just varyed the strobe frequency. At around 60 Hz is what the string was doing, so we basically were suppossed to turn it up, see what happened, turn it down, see what happened.