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Making an Acoustic Levitator - Introduction


About a year ago I came across this video talking about the concept of acoustic levitation and the fact that you can use sound to move objects in mid air. While I was really intrigued I also felt that having such a setup at home would either be really tough to build or would be really expensive. Soon after, I came across a video about a team of electronics and computer science engineers at Bristol University who actually came up with a method to make these levitators really cheap and were even selling and promoting kits to school students to do the same. This made me confident that I might be able to pull it off too....
😝😝😝😝😝😝😝😝😝
Being an engineering student I was told to make a project under something called a "Non-Teaching Credit Course". So I chose this as my project for submission.

SO HOW THE HELL DOES ACOUSTIC LEVITATION WORK???
A short answer of this question could be "Standing Waves", but that doesn't really explain anything, so let me try and simplify things a bit.
We first need a wave like an ocean wave, going up and down forming crests and troughs.
Then we get an obstruction or reflective surface.
When a wave hits the surface it bounces back and moves in the opposite direction towards the source.
But you see, there is already a wave coming from the source, so instead of coming back these two waves interfere with each other.
Sometimes they add up to form a bigger crest or trough and sometimes they cancel out to cause no motion at all.
If you tune the frequency of the wave and the distance between the source and obstruction correctly you get a "Standing Wave" or a wave that looks like its not moving at all.

Its kinda like waving a piece of rope tied at one end to form such shapes as in the image above.....

GOT IT??
YES??
Great!! continue reading!!
NO??
Nevermind!! You don't need to understand to make it!....
(See its like gravity... you don't need to completely understand it to fall down, gravity works anyways. Similarly standing waves will form regardless of you understanding how they work.....)
that's what I love about physics it always works even if you don't get it........                     😝😝😝😝😝😝😝😝😝😝😝😝😝😝😝😝😝😝
So yeah coming back to standing waves........
Thinking about waves, sound is also a wave rather its a wave in air..... so we can have standing waves in air too using sound......!!
If you have standing waves in air, you get high pressure and low pressure bubbles of air between the source and the reflective surface.
In the image the white foggy lines are the low pressure areas.
At the bottom is an ultrasonic speaker to make the standing wave against a glass sheet.

So just by having a speaker against a carefully positioned glass sheet we can make standing waves in air....



Now, if the speaker is powerful enough you can actually place small particles in the low pressure areas and they will float.....!!!!

So all I needed were ultrasonic speakers, an amplifier, a good signal source and that's it....!!


Got any queries??? 
E-Mail me at: shashwath.sundar@gmail.com

Comments

  1. Neelam Mehrotra9 October 2019 at 19:00

    Wowwwww! That’s a fantastic idea ! Keep on working and dreaming always

    ReplyDelete

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