Mind-Blowing Illusion Makes Water Freeze in Mid-AirBy: Chris Gabbard - April 20, 2012
This Video from Youtube user Brusspup shows you how to do a cool science experiment from home that will make water appear to freeze in mid-air.
The sound waves from the speaker will cause the water droplets to fall in a uniform pattern. Combine that with a camera that follows the same frequency in frames per second, and a picture is taken at a time when a new droplet is in the same spot. The effect is that the same droplet is frozen in mid air, when really it is 24 new droplets in the exact same spot.
Tune the Subwoofer to a slightly lower frequency than the fps and the water appears to go back up into the tube.
Brusspop explains how to do it yourself in the video description:
This is really simple but has such an awesome effect. Fill a bucket full of water and place it about 5 feet off the ground. Place a subwoofer about 1 foot lower than the bucket. Run a plastic tube from the top bucket down in front of the subwoofer. Tape the tube to the front of the speaker. Then aim the end of the tube to an empty bucket on the floor. Get the water flowing from the top bucket. Now just generate a 24 hz sine wave and set your camera to 24 fps and watch the magic happen. Basically your cameras frame rate is synced up with the rate of the vibrations of the water so it appears to be frozen or still. Now if you play a 23 hz sine wave your frame rate will be off just a little compared to the sine wave causing the water to “move backward” or so as it appears. You can play a 25 hz sine wave and cause the water to move slowly forward.