one to float over the other. This is known as magnetic levitation.
The Maglev vehicle (say a train) consisting of
5. Very
Strong Magnetic Fields: -
Very strong magnetic fields (of the
order of 50 tesla by consuming only 10 KV) can be generated with coils made of
superconducting materials. The cost of such magnets is quite lesser than
conventional electromagnets.
6.
SQUIDS (Superconducting Quantum Interference Devices): -
SQUIDS are fundamentally
superconducting rings that act as storage devices for magnetic flux. They are
used to detect very minute changes in the magnetic field of a human brain or
body.
7. For
Progress of Computer Technology: -
At present, due to heat generated
through I2R losses, there is a limit to which the components can be crowded
on a chip of given size. The use of superconductors will make it possible to
cram more circuits in a given area.
Q.13 What is nanotechnology? (AKTU. 2011 - 12, 12 - 13)
Ans. Nanotechnology refers braodly to a field of applied science and
technology whose unifying theme is the control of matter on the atomic and
molecular scale, normally 1 to 100 nanometers, and the fabrication of devices
with critical dimensions that lie within that size range.
It is highly multidisciplinary
field, drawing from filed such as applied physics, materials science, interface
and collied science, device physics, supramolecular chemistry (which refers to
the area of chemistry that focues on noncovalent bonding interactions of
molecules), self replicating machines and robotics, chemical engineering,
mechanical engineering, biological engineering and electrical engineering. Much
speculation exists as to what may result from these lines of research.
Nanotechnology can be seen as an extension of existing sciences into the
nanoscale, or as a recasting of existing sciences using a newer and more modern
term.
Q.14 What are the changes in the properties that
take place in a material when its size is reduced to nanoscale. Also explain
the reasons for these
property
changes.
Ans. Materials reduced to the nanoscale can suddenly show very
different properties compared to what they exhibit on a macroscale, enabling
unique applications. For instance opaque substances become transparent (copper); inert material
become catalyst (platinum), stable material turn combustible (aluminium);
solids turn into liquids at room temperature (gold); insulators become
conductors (silicon).
The properties of materials are
different at the nanoscale for two main reasons:
(a) Nanomaterials
have a relatively large surface area as compared to the same mass of material
produced in a larger form. This can make materials more chemically reactive and
affect their strength or electrical properties. In some cases the materials
that are inert in their larger form are reactive when produced in their
nanoscale form.
(b) Quantum
effects can begin to dominate the behaviour of matter at the nanoscale
affecting the optical, electrical and manetic behaviour of materials.
Q.15 What is buckyball? How can buckyballs be
created? Where can these buckyballs be used?
Related
Questions -
Q. Describe buckyballs and their properties
and uses. (AKTU. 2008-09)
Ans. Buckyballs: -
A bucklyball (short for buckminster
fullerence) is a molecule containing 60 carbon atoms. Each carbon atom is
bonded to three adjacent carbon atoms. However the carbon atoms in a buckyball
form a teensy-weensy sphere that is about 1 nanometer in diameter as shown in
figure. While many of the atoms in bulkyballs are connected together in
hexagons, some of the atoms are connected in pentagons.
Creating
Buckyballs: -
Buckyballs could be produced in larger
quantities by vaporizing carbon by placing two carbon electrodes close together
and generating an electric arc between them in a reaction chamber filled with a
low pressure of helium or neon.
Combustion synthesis produces big
enough quantities of bulkyballs at a low enough cost - for use in commercial
applications. This method mixes a hydrocarbon with oxygen and burns the
hydrocarbon at a low pressure.
Properties:
-
Various properties of buckyballs are :
(1) Buckyballs
can be used in various applications because of their chemistry and unusual
hollow, cage-like structure.
