Levitation of objects using a standing ultrasonic wave

T.ChikazawaH.NakayamaR.Makii

It is a sound over 20,000 Hz Short wavelength

Big amplitude.

First, “what is an ultrasonic wave? ”

　① Wave

　② Remains in a constant position

　③ Most vibration ・・・ anti-node

　　 No vibration ・・・ node　 ④Anti-node ~ Node ・・・ ¼ wavelength　　 Node ~ Node ・・・ ½ 　 wavelength

“What is a standing wave ? ”

Using the formula for acoustic velocity

V=fλ 　 V=331.6+0.6t 　 　 V : Acoustic velocity (m/s) 　　　　 　 f 　 : Pitch (Hz)　 λ: Wavelength (m) 　　 t : Temperature (℃ or )

（ m ）　　　　　＝ 8.5(mm)

anti-node ~ node 　 1/4λ ≒2.13(mm) node ~ node 1/2λ

≒4.25(mm) 　　

We can calculate the theoretical levitation position

from this value!!

【 Study motive 】

We were interested in an experiment about acoustic levitation done by last

year’s students.

When we used a ultrasonic wave, we found that the object levitate more

easily.

We studied the relationship between the sound wave and object.

At the beginning……

We used a couple of objects.

We also use ultrasonic wave because it is highly directional.

【 experiment 】＜ Purpose ＞

・ We find whether or not there was only other resistance force causing the objects to float.

⊿x １

【 Expectation 】Acting forces are only 　　　　　　　　　　　　　　　　　‘ gravi

ty’ .

⊿x would have a constant value.

Ⅰ 　・ We levitated object 1.

・ We levitated object 2 , and measured the distance between object 1 and 2.(⊿X1)

【 Experimental method 】

⊿x１

Ⅱ 　・ We levitated object 3 ,and measured the distance between object 2 and 3.(⊿X ２ )

　　・ We also measured the distance between object 1and 2 again.(⊿X ３ )

⊿x ２⊿x ３

  11μm 26μm

⊿X1 4.45mm 4.19mm

⊿X2 4.41mm 4.34mm

⊿X3 4.30mm 4.19mm

【 Result 】Value of each

We showed to graph the average value.

0 1 2 3 4 50

1

2

3

4

5The distance between the ob-

ject 11μ ｍ

26μ ｍ

(mm) The size of the object

Distance

⊿x have a similar value between 4.1mm and 4.5mm.

【 Consideration 】We found that ⊿X is nearly λ/2(≒ ４．２

５ mm) in any case .↓

There is no other resistance force

【 Future 】We want to increase the sample size of our experiment 　　　　　 to make sure that our result are reproducible!

THANK 　　　FOR 　

LISTENING

object⊿X≒λ/2(=4.25mm)