were requested to visit Russel Middle School to show them some
Because the kids
were a little older than our usual Cool Science students we were able
to show them a couple of more advanced demonstrations.
were provided by their teacher because we have enough to do with the
Here we are
considering the range of temperatures that are possible.
From the very
coldest at absolute zero (0 Kelvin, -459.666 Fahrenheit, or -273.15
we are more familiar with like the freezing point of water (273.15 K,
32 F, or 0 C).
And the boiling
point of water (373.15 K, 212 F, or 100 C)
The upper range
of temperatures on the chart are the temperatures of the center of the
sun or in a thermonuclear explosion (10,000,000 K, 10,000,000 C, or
If you wonder
why K and C appear to be equal they actually differ by 273.15 degrees
which hardly matters when you are measuring millions of degrees.
Here is the
chart with lots more points.
Click on it a
couple of times to see an expanded readable version.
Use your back arrow to come come back to this page.
Do you see the
balloon Nancy is holding.
She put a few
cubic centimeters of liquid nitrogen in a bottle then put the balloon
over the neck to catch the gas.
As the liquid
nitrogen boils and returns to a gas it expands more than 700 times and
inflates the balloon.
Meanwhile I continue with other demonstrations distracting the class
from her demonstration.
What do you
think the reaction is when it finally pops.
Nancy froze some
miniature marshmallows and let the kids try them.
marshmallows are such good insulators their surface very quickly warms
up when they touch your tongue so they can be eaten right out of the
Don't try this
with fruit or other things that aren't such good insulators.
Here I was
demonstrating that the resistance of a conductor goes down when it is
The 200 watt
light bulb is barely glowing in the first picture because the
electricity is going through a long wire that is wrapped around the
cylinder I am holding.
When it is
cooled with liquid nitrogen the light glows brightly as expected.
don't just become better conductors they become perfect conductors when
cooled with liquid nitrogen.
That means they
lose all resistance and any current flowing in them continues without
loss as long as they are kept cold.
A magnet brought
near a piece of Yttrium Barium Copper Oxide (Y Ba2 Cu3 O7) Ceramic that has
been cooled will induce a current that will create a magnetic field.
That field exactly opposes the field from the magnet so it floats,
suspended in the air.
balloon animals and put them in liquid nitrogen and the air inside turns to a liquid and they shrink by 700 times.
Take them out
and toss them on the floor and they will grow to their original size.
chemiluminescent light stick can be turned off by immersing it in
temperatures chemical reactions slow down and so no light is emitted.
In fact you can
turn off half of one by only cooling one end.
part of the class is always when we make ice cream in 15 seconds or so.
Somewhere in the
cloud of vapor is our bowl of milk, cream, egg whites, sugar, vanilla,
and a bit of salt that is rapidly becoming ice cream.
If you would like to see these and other demonstrations with closer pictures
and more complete explanations click
Go to the Science Fun main page
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