Aberration
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Aberration is a defect in the
image which is not a true picture of the taken object.
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Abrasion
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A
Phenomenon of wearing off because of friction
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Absolute scale
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The zero
of this scale of temperature corresponds to absolute zero.
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Absolute zero
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Zero of
thermodynamic temperature (0 kelvin)
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Absorption hygrometer
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A device
that is used for measuring the humidity of air
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Acceleration due to gravity(g)
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It is the
uniform acceleration produced in a freely falling body due to the
gravitational pull of the earth.
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Accumulator
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A type of
voltaic cell or battery that can be recharged by passing a current through it
from an external d.c. supply.
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Acceleration (a)
|
The rate
of change of speed or of velocity
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Accelerator
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A machine
used for producing high energy charged particles and studying nuclear
reactions.
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Acceptor
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Materials
that are used for doping semiconductors whose atoms accept electrons form
neighbouring atoms known as host
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Achromatic colour
|
A colour
that has no colour
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Acoustics
|
Refers to
the study of the production and properties of sounds
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Actinometer
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Referes to
any of various instruments for measuring the intensity of electromagnetic
radiation.
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Active device
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An
electronic component such as a transistor that is capable of amplification
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Adapter
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A device
that is used for connecting parts of different size and shape
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Admittance
|
It is a
measure of the ability of a circuit to conduct an alternating current.
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Adsorption
|
The
process of formation of a layer of molecules of one substance on the surface
of a solid
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Aerial
|
The part
of a radio system that transmits energy into or receives from the atmosphere
or space
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Aerosol
|
A
colloidal dispersion of a solid or liquid in a gas
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Air brakes
|
A system
of brakes that is operated by compressed air
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Air conditioner
|
A device
that is used for reducing temperature and humidity of air in an enclosed
space
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Air
|
It is a
gaseous mixture that surrounds the earth.
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Alcohol thermometer
|
A
liquid-in-glass thermometer that uses ethanol as its working substance.
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Allotropy
|
The
existence of a solid substance in different physical forms.
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Alloy
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A mixture
of two or more metals or of a metal with small amounts of non-metals.
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Alnico
|
Used to
make permanent magnets.
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Alternating current (A.C.)
|
A current
which flows alternately in one direction, then in the opposite direction
around a circuit.
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Alternating voltage
|
The
voltage whose magnitude and direction change with time and after a certain
time the voltage recur with the same magnitude and in the same direction is
called alterating voltage
|
Amalgam
|
An alloy
of mercury with one or more other metals
|
Ammeter
|
A meter
used to measure electric current.
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Ampere
|
The ampere
is the practical unit of electric current.
|
Ampere-hour
|
It is a
unit of quantity of electricity
|
Amplifier
|
An
electronic device that is used to increase the strength of an input signal
applied to it.
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Amplitude
|
The
maximum value of a varying quantity from its mean value
|
Analyser
|
A device
for determining the plane of polarization of plane-polarized radiation
|
Anelasticity
|
It is the
property of a solid wherein stress and strain are not uniquely related in preplastic
range.
|
Anemometer
|
It is a
device that is used to measure the speed of wind.
|
Aneroid Barometer
|
It is a type
of barometer
|
Angle of refraction
|
The angle
between a refracted ray and the normal to the surface at the point of
refraction
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Angstrom
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Unit of
length
|
Angular displacement
|
Refers to
the angular or rotational displacement
|
Angular frequency
|
It is equal
to the number of complete rotations made by an object per unit time
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Angular velocity
|
It is the
rate of change of angular displacement
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Anion
|
Negatively
charged ion
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Annealing
|
The
process of heating a solid to a temperature below the melting point.
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Annular space
|
The space
between two rings (inner and an outer)
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Anode
|
The
electrode that is a positive potential with respect to the cathode.
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