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					AMAZING LIQUID NITROGEN


AN AMAZING DISCOVERY….

   In 1772, in his attempts to isolates oxygen and carbon dioxide from the air,
Daniel Rutherford discovered nitrogen. It was also through his
experimentation that Rutherford was successfully able to show the scientific
community that the residual air, consisting mainly of nitrogen, was incapable of
supporting living organisms. Nitrogen makes up approximately 78% of the
volume of the Earth’s air. Oxygen constitutes approximately 21%. The
remaining 1% is made up of fractional percentages of gases such as: Argon,
Carbon Dioxide, Neon, Methane, and Water Vapor.

A COLD BOILING POINT??

   At STP, standard temperature and pressure, nitrogen exists in a gaseous
state. At temperatures well below room temperature, at –320 degrees
Fahrenheit to be exact, nitrogen changes from a gas to a liquid. This makes
liquid nitrogen extremely cold. Remember that the same temperature at which
a substance condenses is the same temperature at which it boils…. so think
about it…nitrogen has a cold boiling point…. weird right?? Most of us tend to
think of the temperature at which something boils to be a high one… but not
the case with nitrogen!

WHY USE LIQUID NITROGEN?

In the liquid state, nitrogen is one of the most widely used cryogenic (extremely
cold) substances. Because it is much cheaper than dry ice or helium and a
much more widely produced cryogenic, it serves as an excellent tool for
medicine, research and classroom demonstrations. Liquid nitrogen provides us
with the opportunity to observe many different thermodynamic processes that
take place when matter is cooled to extremely low temperatures. We’ll learn
more about some of its uses a little later, but for now let’s look how liquid
nitrogen is made.
THE MAKING OF LIQUID NITROGEN:

   A common method for the production of liquid nitrogen is the liquefaction
of air. Liquefaction is the phase change of a substance from the gas phase to
the liquid phase. In liquid nitrogen compressors or generators air is
compressed, expanded and cooled via the Joule-Thompson effect
www.nd.edu/~ed/Joule_Thomson/joule_thomson.htm. Since nitrogen boils at
a different temperature than oxygen, the nitrogen can be distilled out of the
liquid air, re-compressed and then re-liquefied. Once liquid nitrogen is
removed from the distillation chamber it is stored either in a pressurized tank or
a well insulated Dewar Flask. It is then made available for commercial
distribution.

WHY DOES LIQUID NITROGEN SMOKE?

When liquid nitrogen rapidly boils and vaporizes, on a smooth surface with a
temperature that is much higher than nitrogen’s boiling point, a physical
phenomenon known as the “Leidenfrost Effect” is observed. The liquid
nitrogen vaporizes quickly and lifts itself above the surface. It hovers,
producing little or no friction on the surface. If the surface is irregular, this
effect cannot occur and the vaporization is even more rapid. The nitrogen
vapor spreads itself out through the air picking up water vapor along the way.
Liquid nitrogen smokes because of the presence of water in the air. The
amount of water present in the atmosphere is dependent upon the temperature
of the air. Warmer air can hold more water vapor than cooler air. Liquid
nitrogen cools the air to condense the water out of it. These water droplets
scatter light and produce the “smoking” effect. The ability of liquid nitrogen to
do this makes it very popular at parties, magic shows, and in classroom
demonstrations.



                          PICTURES
COMMON USES OF LIQUID NITROGEN:

Freezing and Preservation of Food

- foods can be packed, sealed and then sprayed with liquid nitrogen
- liquid nitrogen evaporates upon contact with many surfaces (including food)
- this evaporation process allows for the absorption of heat and energy from the
  food
- as a result the molecules in the food slow down and the food freezes

“Cryomedicine”

- liquid nitrogen is widely used in the preservation of medical specimens
- it is particularly useful for very long term preservation of cells and tissues
- it may be used for the rapid freezing of different tissues such as bone marrow
  and blood
- it is useful in the preservation of animal embryos, bacteria and fungi
- because extremely cold temperatures can kill human tissue, liquid nitrogen
  may be used in standard medical procedures such as wart removal and
  treatment of certain skin cancers

Research Labs

- many research labs around the world use liquid nitrogen to aid in research
  requiring cryogenic conditions (ie. superconductivity labs)

Classroom Demonstrations

- it should come as no surprise that liquid nitrogen is commonly used in
  the classroom to demonstrate its amazing chemical properties and to illustrate
  its cooling effects on other materials
HERE ARE JUST SOME OF THE FUN EXPERIMENTS THAT CAN BE
DONE WITH LIQUID NITROGEN:

…… BUT WAIT!!….FIRST THINGS FIRST….. SAFETY!!

**** SAFETY FIRST ****

  - liquid nitrogen, like other cryogenic materials, may be harmful if it is not
    handled properly!

  - learn some of the common safety procedures for handling liquid nitrogen
             http://engineering.dartmouth.edu/other/microeng/ln2.html

SHRINKING BALLOONS

     - observe the condensation of oxygen from the air


CRACKING FRUITS AND FLOWERS

   - observe the breaking of some of your favorite rubber polymers, fruits,
       vegetables and flowers


WETTING PAPER

  - observe the rapid evaporation of liquid nitrogen on paper and other
    smooth surfaces


NEWTON’S 3RD LAW WITH PING PONG BALLS

     - observe Newton’s Law of Action-Reaction using a hollow ball
HI-TECH ICE CREAM (ONE OF EVERYONE’S FAVORITE)

     - make creamy ice cream (all sorts of flavors) that’s fun to eat
       in just 15 minutes using liquid nitrogen

     - recipe adapted from “Cooking with Chemistry”
            http:// www.polsci.wvu.edu/Henry/Icecream/Icecream.html


LEVITATE A MAGNET

     - observe the superconductivity of a material below its critical temperature
       (Meissner Effect)

------------------------------------------------------------------------------------------------
                          EXPERIMENTAL ANALYSIS
------------------------------------------------------------------------------------------------

Below you will find some useful information to help analyze what you are
observing in some of the above experiments:

RUBBER/GLASS TRANSITION

   It’s pretty exciting to observe the effects of liquid nitrogen on the physical
properties of elastomers. Elastomer is another term used to describe a rubbery
polymer. Polymers that are elastomers are able to bounce because their chains
can be stretched to many times their original length without being permanently
deformed. Amorphous polymers that are elastomers have low glass transition
temperatures and are soft and pliable at room temperature. Amorphous
polymers that are thermoplastics have high glass transition temperatures and
are hard and glassy at room temperature.
http://www.psrc.usm.edu/acrog/elas.htm
   Glass transition is an amazing phenomenon in which a polymer, when
cooled down below its glass transition temperature (Tg), becomes hard and
brittle. Remember for a hard plastic, like polystyrene, room temperature is
already well below the polymer’s Tg so it will be appear hard and glassy
without additional cooling. Rubber polymers, like rubber balls, may be easily
cooled down below their glass transition temperatures with liquid nitrogen.
When this happens, these polymers can easily lose the ability to bounce or even
shatter into pieces when struck to a hard surface. In fact a rubber ball cooled
below its glass transition temperature becomes rigid like a glass marble and
does not bounce at all. Once it warms up, like other polymers cooled below
their Tg, it becomes soft and bounces again.

SUPERCONDUCTIVITY

    A superconductor is a substance that conducts electricity, without resistance,
when it is cooled below a specific temperature. This temperature is called the
critical transition temperature, or Tc. Click here to see a list of critical
transition temperatures for certain metals
http://www.superconductors.org/Type1.htm. One of the ways that this
phenomenon can be observed is by placing a superconducting material in liquid
nitrogen to cool it down below its Tc. When this happens, these materials
become diamagnetic and are able to completely repel a magnetic field. If a
magnet is then placed near the superconducting material, the material will repel
the magnetic field and the magnet will begin to levitate. Superconducting
material can be purchased (usually in a demonstration kit) from an educational
supply company such as Science Kit and Boreal Laboratories.


LIQUID NITROGEN ICE CREAM

    Texture and taste are very important to the average ice cream fan. Most
people that eat ice cream desire their ice cream tasty, smooth and creamy. In
order for ice cream to possess all of these desired, yummy qualities, the
ingredients need to have the right “chemistry” with each other. Achieving this
is no easy task. Ice cream has a very complex physical structure that, even
until today, is not fully understood by scientists.
        One thing that chemists do know is that the smooth and creamy texture
of ice cream is greatly affected by the size, distribution, shape and number of
ice crystals that form in the ice cream as it freezes. In an attempt to control the
ice-crystal growth manufacturers add different types of natural gums and
stabilizers. Since ice-crystal growth is only one of the factors affecting the
taste and texture of the ice cream, manufacturers must consider the chemical
interactions between all of the ingredients when attempting to make delicious
ice cream. Click here to read more about the chemistry of ice cream:
         http://www.foodproductdesign.com/archive/1997/0897AP.html
    All other factors aside, smaller ice crystal formation in ice cream will give it
a smoother texture. One way to obtain smaller ice crystals in the ice cream is
to promote rapid crystallization during the cooling process. Liquid nitrogen
added to ice cream ingredients (milk, half and half, sugar, and flavoring),
because it is extremely cold, causes a quick drop in temperature and rapid
crystallization of the mixture. Stirring the ice cream mixture will also help
prevent large ice crystals from forming.
    Since liquid nitrogen easily freezes ice cream one might wonder why the ice
cream industry chooses not to use the chemical to manufacture ice cream.
While making ice cream with liquid nitrogen is fun and exciting in the
classroom, it does not provide a practical method to the ice cream industry.
One reason for this is the cost of manufacturing liquid nitrogen. Depending on
the purity of liquid nitrogen, it can costs anywhere from two cents to almost
three dollars per one hundred cubic feet to manufacture (Scientific American
1994 p.66-71). This can add up to some pretty expensive ice cream.
    One ingredient added to ice cream, to help it to freeze evenly, is ice cream
salt. The large ice cream salt crystals lower the freezing point (colligative
property) of the ice cream so that it will need to absorb more energy from the
environment to melt. One thing that you will notice when making liquid
nitrogen ice cream is that it melts faster than commercial ice cream.


ACKNOWLEDGEMENTS:
Faculty, Staff and Students in the Garcia MRSEC program
http://www.powerlabs.org/ln2demo.htm
http://www.dmc.airliquide.com/en/questions.htm
http://www.superconductors.org/Type1.htm
www.polsci.wvu.edu/Henry/Icecream/Icecream/html
www.nd.edu/~ed/Joule_Thomson/joule_thomson.htm
http://www.riverdeep.net/current/2001/09/091701_liquidn.jhtml
http://www.psrc.usm.edu/macrog/elas.htm
http://www.psrc.usm.edu/macrog/tg.htm
http://www.phys.uconn.edu/~csteams/liquid_nitrogen_properties.html
http://www.chemistry.about.com/library/bln.htm
http://engineering.dartmouth.edu/other/microeng/ln2.html
http://www.rsc.org/lap/educatio/eic/2003/clarke_jul03.htm
http://www.foodsci.uoguelph.ca/dairyedu/icstructure.html
http://www.foodproductdesign.com/archive/1997/0897AP.html
                SHRINKI          NG BALL      OONS

OBJECTIVE

Nitrogen makes up approximately 78% of the volume of the Earth’s air.
Oxygen constitutes approximately 21%. The remaining 1% is made up of
fractional percentages of gases such as: Argon, Carbon Dioxide, Neon,
Methane, and Water Vapor. The objective of this experiment is to observe the
cooling effects of liquid nitrogen on different gas components found in the air.
You will observe the expansion, contraction and condensation of these different
gases. Based on your observations, and the background information/reference
charts provided, you will identify the condensed liquid inside of the balloon.
You will also discuss the observed differences in behavior of the balloon filled
with helium and the balloon blown up by you.


MATERIALS

Rubber Balloons (clear works best but any will do)
Non-porous Gloves
Wooden Ruler
Liquid Nitrogen (may be obtained from a chemical supply company)
Helium (if available)
Metal Bowl

PROCDEDURE

(1) Remember that liquid nitrogen is extremely cold and must be handled
    properly!
(2) Wear non-porous gloves to protect your hands.
(3) Fill a rubber balloon with air. Fill a second balloon with helium.
(4) With a wooden ruler, measure the approximate diameter of each balloon.
(5) Dip each balloon in the liquid nitrogen.
(6) Record your observations, such as diameter measurements, liquid
    formation, or crystal formation.
(7) Hold the balloons for a few minutes. Record your observations.


ANALYSIS QUESTIONS

(1) When the balloons were placed in liquid nitrogen did they change size?

(2) Explain what is happening to the gases inside of each balloon as they are
   cooled by liquid nitrogen?

(3) Using the information below identify the liquid inside of the balloon that
    was filled with air:


TEMPERATURES              FAHRENHEIT              CELCIUS        KELVIN

Water Boils                  212                     100            373

Water Freezes                  32                       0           273

Carbon Dioxide Freezes      - 189                   - 123          150

Oxygen Boils                - 272                  - 183            90

Nitrogen Boils              - 320                  - 196           77

Absolute Zero               - 459                   - 273              0


(4) What is the color of the liquid?

(5) Does the condensation of this liquid have practical application?
CRACKING FRUITS AND FLOWERS


OBJECTIVE


Glass transition is an amazing phenomenon in which a polymer, when cooled
down below its glass transition temperature (Tg), becomes hard and brittle.
Remember for a hard plastic, like polystyrene, room temperature is already
well below the polymer’s Tg so it will be appear hard and glassy without
additional cooling. Rubber polymers, like rubber balls, may be easily cooled
down below their glass transition temperatures with liquid nitrogen. When this
happens, these polymers can easily shatter into pieces when struck to a hard
surface. Once the polymers warm up they become soft and bounce again.
The objective of this experiment is to cool some of your favorite rubber
polymers, fruits and vegetables with liquid nitrogen to observe some of the
changes in their physical properties. These properties include their physical
appearance as well as their reaction to hard forces.


MATERIALS

Liquid Nitrogen (may be obtained from a chemical supply company)
Non-porous Gloves
Rubber Balls
Metal Bowl
Fruits and Vegetables of choice (Bananas work great!)
Nails
Piece of Wood
Flowers of choice

PROCEDURE

(1) Remember that liquid nitrogen is extremely cold and must be handled
    properly!
(2) Wear non-porous gloves to protect your hands.
(3) Dip a rubber ball in liquid nitrogen.
(4) Observe the properties and characteristics of the ball when you bounce it on
    the floor. Does it bounce?
(5) Drop the ball several times. Does it make the same sound each time as it
   warms back up to room temperature?
(5) Dip a banana (or food of choice) into liquid nitrogen. Attempt to hammer a
    nail into the piece of wood with it.
(6) Dip a flower into the liquid nitrogen. Record any observations (ie. does the
    flower still have a scent?)
(7) Let these objects cool back to room temperature and observe any
   differences in characteristics.

ANALYSIS QUESTIONS

(1) What is rubber/glass transition? Explain critical temperature.

(2) Why do different substances have different critical temperatures?

(3) Does the rubber ball bounce after it is cooled in the liquid nitrogen?
   Explain the reasons for this behavior/observation.

(4) Were you able to hammer a nail with a piece of fruit that has been cooled
    with liquid nitrogen? Explain the reasons for this behavior/observation.

(5) Discuss what happens to the objects when they are heated back up to room
   temperature. Do you think that the polymer chains have been permanently
   changed or affected? Explain.

(6) What is happening to the molecules in these substances when they are
    exposed to liquid nitrogen. You may use diagrams to illustrate this.

(7) Can all polymers be cooled to a glass transition state?

(8) Discuss some of the practical uses for the freezing effect that liquid nitrogen
    has on living and non-living objects.

(9) Liquid nitrogen has been extremely helpful in the field of medicine (ie.
   freezing cells, blood, and embryo tissue). Are there limits to what liquid
   nitrogen can freeze? Explain.
                    WETTING PAPER
OBJECTIVE

If liquid nitrogen is a liquid then there should be no problem wetting paper with
it right? Well, when liquid nitrogen touches a smooth surface that is at a much
higher temperature than it’s boiling point it begins to boil rapidly and
vaporizes. The liquid nitrogen vaporizes quickly and lifts itself above the
surface. It hovers, producing little or no friction on the surface. This physical
phenomenon is known as the “Leidenfrost Effect.” If the surface is irregular,
this effect cannot occur and the vaporization is even more rapid. The nitrogen
vapor spreads itself out through the air picking up water vapor along the way.
As a result, the liquid nitrogen smokes. The objective of this experiment is to
observe the “Leidenfrost Effect” and the dependence of the smoking effect on
the temperature of the air and the surface of contact.


MATERIALS

Liquid Nitrogen (may be obtained from a chemical supply company)
Non-porous Gloves
Metal Bowl
Smooth paper
Smooth Surface (Table Top or Floor)
Rooms of Different Temperatures (if possible)

PROCEDURE

(1) Remember that liquid nitrogen is extremely cold and must be handled
    properly!
(2) Wear non-porous gloves to protect your hands.
(3) Dip a smooth piece of paper in liquid nitrogen. Feel the paper for moisture.
    Record your observations.
(4) Pour some of the liquid nitrogen across the smooth surface. Be sure that
    there are no people and no objects in the way. Record any observations.
(5) If possible, repeat the experiment on a surface that is not smooth.
(6) If possible, repeat the experiment on a surface of different temperature (ie.
   in another room). Record any changes in observations made.


ANALYSIS QUESTIONS

(1) Were you able to “wet” the paper? Explain the reasons for this observation.

(2) What is the “Leidenfrost Effect?” Were you able to observe this effect?

(3) Why does liquid nitrogen smoke? What is the effect of temperature on the
    amount of smoke observed?

(4) What effect does the texture of the surface have on the amount of smoke
    observed?

(5) What other factors can affect the amount of smoke produced by liquid
    nitrogen?

(6) What are some of the practical applications of this smoking effect?
NEWTON’S 3RD LAW OF MOTION
 WITH PING PONG BALLS
OBJECTIVE

According to Newton’s Third Law of Motion, when two objects collide with
one another, both objects experience forces which are equal in magnitude but
opposite in direction. This is commonly referred to as the Law of Action-
Reaction. While these forces are equal, the acceleration that each object
experiences is not if the two objects are of different masses.
Consider the collision between a baseball player’s bat and a ball. When the bat
collides with the ball, the force experienced by the ball is equal to the force
experienced by the bat. Some would perceive the high speed given to the ball
to be a result of a greater force, when in fact it is a result of an unequal
acceleration. Remember that the bat is more massive than the ball and
according to Newton’s Second Law of Motion, the acceleration of an object is
determined by the force exerted on the object as well as its mass.
The objective of this experiment is to observe Newton’s Law of Action-
Reaction using a ping pong ball and liquid nitrogen.

MATERIALS

Liquid Nitrogen (may be obtained from a chemical supply company)
Non-porous Gloves
Metal Bowl
Ping Pong Balls (or another hollow plastic ball will work fine)
Sharp Object (ie. nail or scissors) to make a hole in the ball
Flat Surface (Table or Floor)
Rubber Balloons
PROCEDURE

(1) Remember that liquid nitrogen is extremely cold and must be handled
    properly!
(2) Wear non-porous gloves to protect your hands.
(3) Make a hole in the ping pong ball with a nail or scissors. Teachers
    may want to do this for the students to avoid injury.

(4) Hold the ping pong ball in liquid nitrogen over the metal bowl. Leave
   the ball in the nitrogen for about one minute.
(5) Take the ball out of the liquid nitrogen and place in on a flat surface.
(6) Record your observations.
(7) Blow up a balloon. Hold it in your hand for a few seconds and then let it
   go. Record your observations.


ANALYSIS QUESTIONS

(1) Discuss Newton’s Three Laws of Motion. Give three examples of each of
    these laws in our everyday lives.

(2) What did you observe when you placed the ping pong ball on the flat
    surface? Explain this observation in terms of Newton’s 3rd Law.

(3) Why was it necessary to poke a hole in the ball at the beginning of the
    experiment?

(4) Will changing the time that the ball is in contact with the liquid nitrogen
    change the reaction time? You may want to test your hypothesis.

(5) What did you observe when you let go of the blown up balloon? Explain
    this observation in terms of Newton’s 3rd Law.
  HIGH TECH ICE CREAM

OBJECTIVE

        Texture and taste are very important to the average ice cream fan. Most
people that eat ice cream desire their ice cream tasty, smooth and creamy. In
order for ice cream to possess all of these desired, yummy qualities, the
ingredients need to have the right “chemistry” with each other. Achieving this
is no easy task. Ice cream has a very complex physical structure that, even
until today, is not fully understood by scientists.
        One thing that chemists do know is that the smooth and creamy texture
of ice cream is greatly affected by the size, distribution, shape and number of
ice crystals that form in the ice cream as it freezes. Smaller ice crystal
formation in ice cream will give it a smoother texture. One way to obtain
smaller ice crystals in the ice cream is to promote rapid crystallization during
the cooling process. Liquid nitrogen added to ice cream ingredients (milk, half
and half, sugar, and flavoring), because it is extremely cold, causes a quick
drop in temperature and rapid crystallization of the mixture.
        The objective of this lab is a yummy one. You will use liquid nitrogen
to freeze the ingredients of ice cream together in less than 20 minutes. So
gather the ingredients, stir in some liquid nitrogen and ENJOY!! Oh and don’t
forget your favorite toppings!!

MATERIALS

Liquid Nitrogen (may be obtained from a chemical supply company)
Stainless Steel Mixing Bowl
Wooden Mixing Spoon
Non-porous Gloves
Level counter or Sink
Cups
Plastic Spoons
Ice Cream Recipe (recipe adapted from “Cooking with Chemistry”
     http://www.polsci.wvu.edu/Henry/Icecream/Icecream.html

  For approximately 1 Gallon of Ice Cream:

5 gallons of Liquid Nitrogen (for every 1 gallon of ice cream)
1 cup of sugar
1 1/2 quarts of milk
3 quarts of heavy cream
8 tablespoons of vanilla
flavoring/toppings


PROCEDURE

(1) Remember that liquid nitrogen is extremely cold and must be handled
    properly!
(2) Wear non-porous gloves to protect your hands.
(3) Pour the milk and cream into the mixing bowl.
(4) Stir the sugar into the mixture to dissolve it.
(5) Put in vanilla (or other flavoring).
(6) Stir in liquid nitrogen, with a wooden spoon, to freeze the mixture. Stop
    periodically to check for large ice crystals and clumping. The liquid
    nitrogen smokes so it will be difficult to see.
(7) Serve and enjoy!!


ANALYSIS QUESTIONS

(1) Why is liquid nitrogen safe to eat?

(2) What is a cryogenic substance? What precautions should be taken when
    handling one?

(3) Why does liquid nitrogen smoke? What are some of the factors affecting
    the amount of smoke produced?

(4) What are the benefits of using liquid nitrogen for making ice cream?
(5) Why do ice cream manufacturers choose not to use liquid nitrogen?


(6) How is ice cream manufactured? What makes it smooth and creamy?

(7) Why is ice cream salt used in the production of ice cream? Be sure to
    explain colligative properties in your answer.

(8) Approximately how long does it take for the liquid nitrogen ice cream to
    melt? Is this melting time different from the melting time of manufactured
    ice cream? Explain the reason for this observation.

(9) What are some of the practical/everyday applications of liquid nitrogen?
SUPERCONDUCTIVITY
OBJECTIVE

    A superconductor is a substance that conducts electricity, without resistance,
when it is cooled below a specific temperature. This temperature is called the
critical transition temperature, or Tc. When this happens, these materials
become diamagnetic and are able to completely repel a magnetic field. If a
magnet is then placed near the superconducting material, the material will repel
the magnetic field and the magnet will begin to levitate. The objective of this
experiment is to observe the levitation of a magnet by a superconducting
material when it is cooled below its Tc with liquid nitrogen.

MATERIALS

Liquid Nitrogen (may be purchased from a chemical supply company)
Superconducting Material (may be purchased as part of a demonstration kit
      from an educational supply company such as Science Kit and Boreal
      Laboratories)
Non-porous Gloves
Metal Bowl
Magnets of different sizes

PROCEDURES

(1) Remember that liquid nitrogen is extremely cold and must be handled
    properly!
(2) Wear non-porous gloves to protect your hands.
(3) If you have purchased a kit follow the instructions included.
(4) Place the superconductive material in the liquid nitrogen.
(5) Place a magnet on top of the material. Record your observations.
(6) Repeat this with a magnet of different size. Record your observations.
(7) Take the superconductive material out of the nitrogen and place it on the
    flat surface. Place the magnets on top of the material. Record your
    observations.
ANALYSIS QUESTIONS

(1) What is superconductivity? Be sure to explain the Meissner effect and
    critical temperature in your response.

(2) Are all materials superconductive?

(3) What did you observe when the material was in liquid nitrogen and when
    it was not. Explain the reasons for these observations.

(4) What did you observe when the size of the magnet changed? Explain the
    reasons for these observations.

(5) Discuss some of the benefits of using superconductors in technology
    and medicine on the macro and micro scales.

				
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