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
Gay-Lussac’s
Law
At constant
volume, the pressure of a given mass of gas is directly proportional to its
absolute temperature.
Geiger
Muller Counter
In 1928, Geiger
& Muller in Germany developed this counter. The counter is used for
detection of level of radiation. The device is a gas filled type radiation
detector working in Geiger Muller region, in which the pulse height output is
same for any event occurring inside the counter. Essentially they all have a
metallic cylindrical cathode with a Tungsten wire of about 0.1mm diameter
stretched along its axis. The wire which is insulated from cathode serves as
anode. The evacuated counter is filled with suitable gas along with quenching
gas at vacuum pressure. The counters are usually used to detect radiation of
low energy level.
Geiger-Nuttal
Law
This law implies
an empirical relation between range of an alpha particle ‘R’ and decay constant
‘λ’ of
alpha emitter as Log R = A Log λ + B Where ‘A’ is a constant having same value
for all three radioactive series and ‘B’ is constant, different for each
series. This law has acquired prominence in nuclear physics because it enabled
physicists to estimate half lives of alpha emitters which couldn’t be easily
determined by experimental results.
Generalized
Coordinates
A set of
variables used to specify the position and orientation of a system, in
principle defined in terms of Cartesian coordinates of systems particles. The number
of such coordinates equals the number of degrees of freedom set of the system
also known as Lagrangian coordinates.
Geocentric
Theory
Theory proposed
by Ptolemy, as per which all the planets and the sun revolve round the earth.
Geocentric
Relating to a
model of the solar system or universe, having the earth as the centre.
Geomagnetism
The branch of
geophysics which deals with study of magnetic field associated with earth.
Geophysics
It is study of
the earth by quantitative physical methods, especially by seismic reflection
and refraction, gravity, magnetic, electrical, and electromagnetic and
radioactivity methods. It includes branches of seismology (earth quakes &
elastic wave), gravity & geodesy (earth’s gravitational field, size and
form of earth) and the atmospheric pressure.
Geo-stationary
Satellite
A satellite which
appears to be stationary relative to the earth is called as geo-stationary
satellite. The direction of motion and magnitude of orbital velocity of
satellite are same as that of earth. The time period of revolution of a parking
satellite is 24 hours. Height of the geo-stationary orbit above the surface of
earth is about 36000 KM.
Giant
Stars
Stars, which have relatively larger radius
for its mass and temperature that burns Hydrogen at much faster value than a
dwarf star. They are much more luminous and have shorter life spans. They
usually end their lives as supernovae.
Gibbs
Energy Function
Thermodynamic
Function at isothermal (const temp) & isobaric conditions (constant
pressure).
Mathematical
expression is G = G
(T, P, N) ; G= H - TS
Gibbs
Paradox
An unaccountable
increase of entropy by 2NKlog2 even when allowing the mixing of two same gases
which is against the result in agreement with thermodynamic reversible process
i.e., change in entropy should be zero. ‘N’
is total no. of gas molecules in ensemble and ‘K’ is Boltzman constant.
Gilbert
It is unit of magnetic potential. It is the magnetic
potential against which one erg of work is done when unit magnetic pole is
transferred.
Gluon
A quantum of color field that binds quarks
into nucleons and also nucleons into nuclei is called as Gluon.
GM
Region
One of the six
regions of operation, in which gas filled radiation detector, may be operated.
In this region of operation, the gas multiplication is so high that the final
total charge formed is independent of initial ion pairs formed by impinging
radiation which is because of mechanism called ‘Geiger Discharge’.
Gold
Leaf Electroscope
Device used to
detect electric charge. It was one of the most popular instruments used by
scientists to study electricity. An electroscope has a thin layer of gold
leaf attached to a metal stem. When the electroscope is charged the leaf is
repelled by the stem and rises.
Gradient
Gradient is a vector operation which operates on a scalar function to produce a vector whose magnitude is the maximum rate of change of function at the point of gradient and which pointed in direction of maximum rate of change. If ‘S’ is a surface of a constant value for function f(x,y,z) then gradient on surface defines a vector which is normal to the surface.
