Tip:
Highlight text to annotate it
X
hi!
I'm Reza and with my team today we're going to tell you about
an amazing phenomenon, the floating water bridge.
let's see how it's done. so we have two beakers
filled with deionized water and connected to a power supply which can
produce about 20,000 Volts.
applying the voltage a connection of water is formed.
now when the beakers are pulled apart, we will have a
bridge of water, defying gravity
and hanging between the beaker tips.
it lasts for hours and can be as long as 25 millimeters.
we were first introduced to this effect doing the 25th IYPT
which is an international research based tournament for high school students.
we continued our study at medical physics lab at Sharif University of
Technology
Where Nima, Peyman and professor Amjadi joined the team.
When we started our research
no one really knew what force it is that holds the bridge!
the phenomenon was first discovered more than a century ago by Sir Armstrong
was not studied until 2007 when it was discovered
again. since then, many researchers try to solve the mystery.
but what holds the bridge? why doesn't it simply fall?
this was a very challenging question. maybe it is the water molecules forming
chain-like
structures in the electric field. many people thought so,
but experiments disagreed. to find the answer
we did quantitative experiments, analyzed them precisely and estimated the
forces.
having the exact values from our measurements, we could compare the results with the theories
to see which one is in agreement. the outcome was quite impressive.
finally we found the correct explanation.
and this was a breakthrough highlighted in science magazine's news.
we showed is classical forces, the sum of surface tension
and dielectric tension that hold the bridge against gravity.
still there was much more to be found out,
so we decided to continue the research. that was where Zahra joined us in the team.
We thought what else we can do to learn more about this phenomenon,
so we came up with the idea of perturbing the bridge.
as a mechanical perturbation
we let some particles fall on the bridge and see its behavior.
we tried particles of salt, sugar
and even metal. Metal is conductive,
and salt changes water's conductivity, and therefore
destruct the bridge. We also tried to perturb to bridge electrically.
while doing so, Nima found an interesting thing happening to the bridge when
subjected to a special kind of oscillatory voltage.
We called it the dancing bridge.
We also tried to experiment the bridging in a vertical setup,
which has less geometrical complexities. We found out that
in special cases to bridge oscillates in different kinds
of modes, although a constant direct voltage was used.
well, that was the result of about one year on research, performed mostly by
undergraduate students.
our research however, is to be continued. thanks for watching!