A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Critical
Temperature
The highest
temperature, below which a gas can be liquefied only by increasing the pressure
and above which a gas cannot be liquefied how so ever high pressure may be
applied.
Critical
Volume
Volume of unit
mass of gas at the critical temperature and critical pressure is called
critical volume of gas.
Crookes
Tube
A Crookes tube is
an electric discharge invented by British chemist and physicist William Crookes
in the early 1870’s. It consists of a sealed glass tube which is evacuated to
an air pressure between 0.005Pa and 0.1Pa and incorporates two electrodes
(cathode and anode) connected to external DC power supply. When high voltage is
applied to the tube, electric discharge in the rarefied air inside the tube
ionizes some air molecules. Positive ions move in the electric field toward the
cathode and create more ions through collisions with air molecules. As positive
ions strike the cathode, electrons are released from the cathode, move toward
the anode in the electric field that is present between the cathode and
anode.
Cross
Product
Cross product of
two vectors is a vector whose magnitude is equal to the product of magnitudes
of those two vectors and the sine of angle between them. Direction of this
vector is perpendicular to plane containing those two vectors.
Crossection
It is defined as
the probability that an event may occur when a single nucleus is exposed to a
beam of particles of total flux containing one particle per unit area.
Cryocan
Container used to
store super cooled liquids like liquid nitrogen. They are designed in such a
fashion to minimize heat transfer due to radiation, conduction or convection.
Cryogenics
Study of low
temperatures less than -150 oc including production of low temperatures and behavior
of materials at low temperatures is called as Cryogenics.
Cryoscope
Instrument used to determine freezing point of a
substance.
Cryotron
It is magnetically controlled
electronic switching device that operates at extremely low temperatures. It
uses principle of varying magnetic field that can cause resistance of a
superconducting element to change rapidly between its high normal and low
superconductive values. It is used as a switch and as a computer memory
element.
Crystal
Momentum
It is momentum
associated with dynamical behavior of electron in periodic potential. It is
defined as product of effective mass of electron and group velocity associated
with electron in periodic potential.
Crystal
Oscillator
Oscillations made
from crystals exhibiting Piezo-electric effect. These oscillators oscillate at
constant frequency which changes by less than 0.1% due to temperature and other
changes.
Crystal
Structure
For crystalline
materials, the manner in which atoms or ions are arrayed in space is conveyed
by crystal structure. It is defined in terms of unit cell geometry and the atom
positions within the unit cell.
Crystal
System
It is a scheme by
which crystal structures are classified according to unit cell geometry. This
geometry is specified in terms of relationships between edge lengths and inter-axial
angles. There are seven different possible combinations of 3 edge lengths and 3
inter-axial angles referred to as crystal systems.
Crystal
Material in which
atoms are situated in a repeating or periodic array over large atomic
distances; that is long range order exists such that upon solidification, the
atoms will position themselves in a repetitive three dimensional pattern, in
which each atom is bonded to its nearest neighbor atom.
Crystalline
Defect
A lattice
irregularity having one or more of its dimensions on order of atomic diameter
is called as crystalline defect.
Crystalline
The state of a
solid material characterized by a periodic and repeating atomic arrangement is
achieved by molecular chain alignment.
Crystallite
A region within a
crystalline polymer in which all the molecular chains are ordered and aligned
is called as crystallite.
Crystallographic
Direction
It is defined as
vector between two points in a crystal lattice.
Curie
Law
The intensity of magnetization is I=AH/T ; ‘H’ is magnetic field strength, ‘T’ is absolute
temp, ‘A’ is curies constant. It is applicable for paramagnetic substance.
Curie
Temperature
The temperature
above which a Ferromagnetic Material becomes paramagnetic is called as Curie
temperature.
Curie
It is the unit
used to describe the strength of a radioactive source in terms of number of
disintegrations it undergoes in a unit time. It is designated by Ci. One curie
equals 3.7 x 1010 disintegrations per second. It has originated
based on rate of decay of a gram of Radium. Experiments have yielded the result
that there are about 3.7 x 1010 disintegrates per second per gram of
Radium. This number is taken as standard and called as Curie.
Curie–Weiss
Law
The Curie law was
modified by Weiss to state that susceptibility of a paramagnetic substance
above the Curie point varies inversely as excess of temp above that point. This
law is not valid at or below Curie point.
Current
(Electric)
The net charge
flowing through a crossection of a conductor in unit time is called current.
Cyclic
Process
It is a process in
which a system undergoes a series of changes and ultimately comes back to
initial state.
Cyclotron
Type of
accelerator invented by Ernest Lawrence of university of California, Berkely,
in 1932. The 1939 noble prize in physics was awarded to Lawrence for the
invitation and development of the cyclotron.
Cyclotron is a particle accelerator used to accelerate charged particles
using high frequency alternating voltage applied between two “D” shaped
electrodes. A static magnetic field is applied perpendicularly to the plane of
electrons for accelerating particles at same phase. Particles escape electrodes
by traversing spiral path.
