Demos

farrowbrainUrban and Civil

Nov 15, 2013 (3 years and 8 months ago)

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Slade Elementary Science Day Mini
-
Experiments

1


Optics

Materials:

1.

Saucer

Saucer with figure

2.

Box

Box

3.

Color Cards

Remake color cards
, push pins

(pen or pencil)

4.

Size Cards

Remake size cards

5.

Fiber Optics?

Laser

pointer
, Fiber optics
strands, Fiber optic shapes

Directions:

1.

Saucer

Use Harry Plopper (song)? Get a volunteer to point at HP with the laser
pointer. What happens? Open up saucer. It’s a mirage.

2.

Box

Show students box. Put some change in the box. How can I do that? Open up
box.

3.

Color Cards

(Benham’s Disk)

Spin the cards. What happens? You can see colors.

4.

Size Cards

There is four possible ways to set these up:






Which one is bigger?

Background

1.

Saucer


Paraboloid mirrors create a mirage or a hologram.

2.

Box

There is a mirr
or placed at an angle

which makes the box look like its
floating.

3.

Color Cards

Benham's top

From Wikipedia, the free encyclopedia

A sample of a Benham's disk

Benham's top
, also called Benham's disk, is named after the English toymaker
Charles Benham
, who, in 1895, sold a top painted with the pattern shown at
right. When the disk is spun, arcs of pale color


called
Fechner colors

or
pattern induced flicker colors (PIFCs)


are visible at different places on the
disk. Not everyone sees the same colors.

The phenomenon is not entirely
understood. One possible reason people see colors may be

that the
color
receptors

in the human eye respond at different rates to red, green, and blue. Or,
more specifically, that the latencies of the centre and the surrounding
mechanisms differ for th
e different types of color
-
specific ganglion cells.

The
phenomenon originates from neural activity in the
retina

and spatial interactions
in the
primary visual cortex
, which processes pattern recognition.
[1]

Research
indicates that the blue
-
yellow
opponent

process

accounts for all the different
PIFCs.
[2]

Benham's top and other PIFCs are being researched for use as a
diagnostic tool for diseases of the eye and the visual track. It has

shown
particular promise in detecting
Optic neuritis
.
[3]

Cone cell

From Wikipedia, the free encyclopedia


(Redirected from
Color receptors
)

Normalized
responsivity

spectra of human cone cells, S, M, and L types

Cone
cells
, or
cones
, are
photoreceptor cells

in the
retina

of the
eye

which
function best in re
latively bright
light
. The cone cells gradually become more
sparse towards the periphery of the retina.

A commonly cited figure of six million in the human eye was found by
Osterberg
[1]

in 1935. Oyster's textbook (1999) cites work by Curcio et al. (1990)
indicating an average closer to 4.5 million cone cells and 90 million
rod cells

in
the human retina.
[
citation needed
]

Cones are less sensitive to light than the
rod cells

in
the retina (which support
vision at low light levels), but allow
the perception of color
. They are also able to
perceive finer detail and more rapid changes in images, because their response
times t
o stimuli are faster than those of rods.
[2]

Because humans usually have
three kinds of cones, with different
photops
ins
, which have different response
curves, and thus respond to variation in color in different ways, they have
trichromatic vision
. Being
color blind

can change this, and there have been
reports of people with four or more types of cones, giving them
tetrachromatic

vision.

4.

Size Cards

Depending on how you turn them the
different colored arcs appear to be
different sizes even though they actually are the same size.

5.

Fiber Optics

Used in electronics instead of wires. Telecommunication… Total internal
reflection…



Liquid Nitrogen

Materials:

Slade Elementary Science Day Mini
-
Experiments

3


Liquid Nitrogen, Gloves, Large St
yrofoam container, Styrofoam cup,
Tupperware Bin, Tablecloth
, Caution tape

1.

Rose

Rose, Styrofoam cup half full of LN2, Gloves

2.

Cork pop

Cork and tube, Small cup with one dram LN2, Gloves

3.

Balloon

Balloon, Test tube, Small cup with one dram LN2, Gloves

4.

Hot
water and bubbles?

Hot water, Dishwasher detergent, Food coloring, Large Styrofoam container,
Gloves, Styrofoam cup full of LN2

5.

Graham Crackers

Graham crackers, Styrofoam cup, Tongs, Gloves

Directions:

1.

Rose

Use the gloves. Place the rose in a half full Sty
rofoam cup of LN2. Remove
after ~10 seconds and crush in a gloved hand.

2.

Cork pop

Use the gloves. Pour about one dram worth of LN2 in the small cup from the
Styrofoam cup. Pour from the Styrofoam cup into the tube. Quickly and
smoothly cork the tube. The co
rk pops within one second. The more seamless
the corking the more times the cork can be popped.

3.

Balloon

Blow the balloon up and place it on the test tube. Place the balloon and test
tube combo in the large Styrofoam container. Pour the half full Styrofoam
cup
of LN2 over the combo, wait for the balloon to shrink. Pull out the combo and
watch the balloon expand again.

4.

Hot water and bubbles

Fill the large Styrofoam container half full with hot water. Put a couple of tsp
of dishwashing detergent in the contain
er, you could also add food coloring.
Use the gloves and add a Styrofoam cup full of LN2.

5.

Graham crackers

Using tongs and gloves place a piece of graham cracker in LN2 for about 10
seconds. Pull out and wave around vigorously for 10 seconds. Get a student
to voluntarily eat a cracker and watch him/her steam away!

Background:

Cold


Wh
at’s the temperature outside (22
-
40

F)? How about room temperature (70
F)?
Wyoming’s record low is
-
66F! Where (Yellowstone)? Earth’s record low is
-
129F! Where (Antar
c
tica)?
L
N2 has a really low boiling point, in order to get LN2 to
be liquid it needs

to be at 77K (that’s about
-
321

F!).

Phase


What is this LN2 doing (boiling)? What is water’s boiling point (
212

F)?
What does boiling mean (changing liquid to gas)? What takes u
p more room liquid
or gas (gas)? When LN2 phase changes to gas it expands to about 2000 times its
liquid

volume.

LN2 Cautions


Non
-
toxic, Non
-
combustible, BUT liquid to gas expansion factor of
2000 therefore airtight seals are hazardous, and extremely col
d therefore prolonged
exposure results in frostbite!

We use LN2 to cool down electronics (work better
when they are cold). Atomic number = 7, atomic mass = 14.007, 78% of earth’s
atmosphere.

We (astrophysicists) use LN2 to cool down electronics (CCD camera
, work
more
efficiently

when they are cold
, reduce the number of false e
-

signaling

from random
thermal bumping
)
.



in the study of
cryogenics



as a source of very dry nitrogen gas



the immersion freezing and transportation of
food

products



the
cryopreservation

of
blood
, rep
roductive cells (
sperm

and
egg
),
and other
biological

samples and materials



as a cooling supplement fo
r
overclocking

a
central processing unit
, a
graphics proces
sing unit
, or another type of
computer hardware
[3]



as a method of freezing water pipes in order to work on them in
situations where a tap is not available to block water flow to the work
area.



in
cryotherapy

for removing unsightly or potentially
malignant s
kin
lesions

such as
warts

and
actinic keratosis
.



in the process of
promession
, a way to

dispose of the dead.



cooling a
high
-
temperature superconductor

to a temperature
sufficient to achieve
superconducti
vity
.



the
cryonic preservation of humans and pets

in the hope of future
reanimation.