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larisa [96]
3 years ago
13

What is the surprising thing that happens in a superconductor?

Physics
1 answer:
PIT_PIT [208]3 years ago
7 0

With almost all substances . . .

-- when you cool them, their electrical resistance decreases.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.

-- If you keep making them colder, their resistance keeps decreasing,
but it never completely disappears, no matter how cold you make them.


But with a few surprising substances, called 'superconductors' . . .

-- when you cool them, their electrical resistance decreases.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.

-- If you keep making them colder, then suddenly, at some magic
temperature, their resistance COMPLETELY disappears.  It doesn't
just become small, and it doesn't just become too small to measure. 
It becomes literally totally and absolutely ZERO. 

If you start a current flowing in a superconducting wire, for example,
you can connect  the ends of the wire together, and the current keeps
flowing around and around in it, for months or years.  As long as you
keep the loop cold enough, the current never decreases, because
the superconducting wire has totally ZERO resistance.

Did somebody say "What's this good for ?  What can you do with it ?"

1).  Every CT-scan machine and every MRI machine needs many
powerful magnets to do its thing.  They are all electromagnets, with
coils of superconducting wire, enclosed in containers full of liquid helium. 
Yes, it's complicated and expensive.  But it turns out to be simpler and
cheaper than using regular electromagnets, with coils of regular plain
old copper wire, AND the big power supplies that would be needed
to keep them going.

2).  Resistance in wire means that when current flows through it,
energy is lost.  The long cables from the power-generating station
to your house have resistance, so energy is lost on the way from the
generating station to your house.  That lost energy is energy that the
electric company can't sell, because they can't deliver it to customers.

There are plans to build superconducting cables to carry electric power
from the producers to the customers.  The cables will be hollow pipes,
with liquid helium or liquid hydrogen inside to keep them cold, and
something on the outside to insulate them from the warmth outside.
Yes, they'll be complicated and expensive.  But they'll have ZERO
resistance, so NO energy will be lost on its way from the generating
stations to the customers.  The power companies think they can
build superconducting 'transmission lines' that will cost less than
the energy that's being lost now, with regular cables.
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UNO [17]

Answer: a) speed = 3.45 × 10^-2 m/s

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3 0
4 years ago
A uranium nucleus is traveling at 0.94 c in the positive direction relative to the laboratory when it suddenly splits into two p
Anettt [7]

Answer:

A   u = 0.36c      B u = 0.961c

Explanation:

In special relativity the transformation of velocities is carried out using the Lorentz equations, if the movement in the x direction remains

     u ’= (u-v) / (1- uv / c²)

Where u’ is the speed with respect to the mobile system, in this case the initial nucleus of uranium, u the speed with respect to the fixed system (the observer in the laboratory) and v the speed of the mobile system with respect to the laboratory

The data give is u ’= 0.43c and the initial core velocity v = 0.94c

Let's clear the speed with respect to the observer (u)

      u’ (1- u v / c²) = u -v

      u + u ’uv / c² = v - u’

      u (1 + u ’v / c²) = v - u’

      u = (v-u ’) / (1+ u’ v / c²)

Let's calculate

      u = (0.94 c - 0.43c) / (1+ 0.43c 0.94 c / c²)

      u = 0.51c / (1 + 0.4042)

      u = 0.36c

We repeat the calculation for the other piece

In this case u ’= - 0.35c

We calculate

       u = (0.94c + 0.35c) / (1 - 0.35c 0.94c / c²)

       u = 1.29c / (1- 0.329)

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6 0
3 years ago
Which of the following compounds is not likely to have ionic bonds? Question 5 options: LiF NaCl CH4 MgF2
Harrizon [31]

Answer:

CH4

Explanation:

CH4 is joined together by a covalent bond, aka a bond between two non-metals. Non-metals are found on the right side of the periodic table and include Carbon (C) and Hydrogen. Although Hydrogen is technically on the left side of the table, it has the characteristics of a non-metal. Futhermore, Ionic bonds generally are between an element on the right joined with an element on the left. This is because ionic bonds want charges that will cancel out to create a neutral molecule.

example: LiF

Li→ Li+

F→F-

(Li+)+(F-)=charges cancel out.

7 0
3 years ago
Where does the majority of earth's water reside?
tensa zangetsu [6.8K]
Depends on which, most pf water in general resides within the ocean but fresh water resides mostly within ice caps in the arctic, Hope this helps
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3 years ago
in a _system supply and demand forces affect the production and consumption decisions. There is little to no _control in such a
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Answer:

in a free market system supply and demand forces affect the production and consumption decisions. There is little to no government control in such a system .

Explanation:

A free market is an economic system in which prices are based on competition between private actors and are not affected by other factors besides supply and demand, that is, where there are no external variables that condition the market.

Free market economy systems are characterized by limited government intervention, which characterizes democratic, liberal states and the modern global economy, in which the market in its private face makes most of the economic decisions, leaving the government a minimum amount of necessary regulations.

5 0
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