1. Sonoluminescence Chris McFarland Ryan Pettibone Emily Veit

2. The Basics Set up a standing pressure wave in some fluid. Trap a bubble at the antinode of the wave. The pressure waves alternately compress and rarefy the bubbles adiabatically. The compressed gas in bubbles reaches a high temperature, and radiates by some unknown process. Easy enough, right?

3. WRONG!

4. Experimental Setup/Procedure Set L=0, set signal generator to flask resonance. Adjust inductor to achieve RLC resonance. Pull water out of flask, drip back in to make bubbles. Sig. Gen. Osc. Flask Syringe L Amp.

5. Our objectives: Find Resonance of flask, “trap” a bubble, and…

6. MORE POWER!!

7. Innovation: Resonance We found powerful resonant peaks at 52KHz, 77KHz, 270 KHz. We believe that these are resonances because: The input to the transducers was constant over this range, and when you change the water level, the resonant peaks change.

8. Resonance Frequencies Found

9. Resonance Properties

10. Innovation: The Amplifier RfRi Vi Vo Vo/Vi=-Rf/Ri We used this circuit to boost Vo.

11. Innovation Inductor: With the inductor tuned, we achieved 80Vpp across the transducers, and an 8Vpp microphone signal. RLC Resonance was achieved with L ~ 8 mH. Thus, C transducers ~ 5 nF. Cleaned flask/syringes with ethanol Water: Degassed, distilled water was used. Put up more curtains

12. Qualitative Observations We did “trap” bubbles, that is, bubbles hovered at the flask at antinodes. When this occurred, changing the frequency caused the bubbles to abruptly move, indicating that sound waves were influencing the motion of bubbles in flask. Bubbles appear to “quiver,” indicating a change of radius.

13. Experimental Issues Chris: His hair caused the infamous “Dandruff Effect” in the last lab: this time he broke an expensive lab amplifier. When you pull water out of flask to make a bubble, the flask falls out of resonance. It’s hard create bubbles without hitting the flask with the syringe.

14. Conclusion We achieved a mic voltage of up to 8Vpp, higher than the last group. This and qualitative observations suggest we were very close to achieving SL. The only difference: We used the 52 KHz resonant peak. Why didn’t we see a strong resonance at 31 KHz??

15. Suggestions to Next Group Fix our experimental issues Use argon gas to make bubbles Find a way to cool flask Glue more transducers to flask? Pray.

16. QUESTIONS??