Anelasticity
In
some engineering materials, there also exists time dependent elastic strain
component. That is elastic deformation will continue even after stress
application and upon load release, some finite time is required for complete
recovery. This time dependant elastic behavior is known as anelasticity.
Anemometer
The
term is derived from Greek word “anemos”, meaning wind. It is device used for
measuring speed of air flow in wind tunnels, and in other gas flow
applications.
Angle
The
amount of space between two straight lines having a common end point usually
measured in degrees.
Angle of
Incidence
Angle
between incidence ray and normal to the surface is called angle of incidence.
Angle of Minimum
Deviation
When
the angle of incidence in a prism is increased, the value of angle of deviation
first decreases and then increases. The minimum value of deviation is called
the angle of deviation.
Angle of
Reflection
It
is the angle between reflected ray and normal to the surface, from which light
is reflected.
Angle of
Refraction
It
is the angle between refracted ray and the surface from which light is
refracted.
Angstrom
It
is the unit of length usually used to express sizes at atomic scale. It is
equal to 10-10 meter.
Angular Acceleration
It
is defined as the rate of change of angular velocity.
Angular Aperture
Angular
aperture of an objective is largest angular extent of wave surface which it can
transmit.
Angular Displacement
When
a particle describes circular path, the angle described by the radius vector in
a given time interval is called angular displacement. Its direction is
perpendicular to plane of rotation along the axis.
Angular Momentum
It
is the ability of a body by virtue of which it imparts rotatory motion to other
bodies. Angular momentum is product of linear momentum and perpendicular
distance of direction of linear momentum from center of rotation.
Angular
velocity
It is defined as rate of change of angular
displacement.
Anisotropy
It
is the phenomenon of exhibiting different values of a physical property in
different crystallographic directions.
Annealing
It
is the process of heat treatment of metal by which microstructure and
consequently properties of a material are altered. Annealing is generally
heating of metal to specific temperature, for certain duration and then allowed
to cool slowly thus softening by re-crystallizing. Cold worked metals usually
undergo this for relieving strain.
Anode Rays
Rays
of positively charged particles formed inside gas discharge tubes. These rays
were discovered by Goldstein in 1886.
Anode
It
is the electrode in an electrochemical cell that experiences oxidation, or
gives up electron.
Anodizing
It
is an electrochemical metal finishing process used for increasing thickness and
toughness of the naturally occurring protective oxides on surface of metals.
The process is called anodizing, as the part to be chemically treated forms the
anode electrode of electric circuit. The process increases non-corrosiveness
& non-conductivity.
Anomalous Dielectric
Dispersion
The
fall in permittivity of a dielectric material with increasing frequency of
external electric field is a phenomenon called anomalous dielectric
dispersion.
Anomalous Expansion
of Water
When
temperature of water is raised from 0 oC, its volume decreases up to
4 oC and above 4 oC its volume increases. This is called
anomalous expansion. It is due to formation of more number of Hydrogen bonds.
Anomalous
Zeeman Effect
When
spectral lines of an atom split into three or more unequally spaced lines in
the presence of magnetic field then the phenomenon is called as anomalous
Zeeman effect. This usually happens for the systems where net spin i.e. spin
quantum number is not zero.
Antenna
A
type of transducer that converts RF fields into alternating current or vice
versa. A receiving antenna intercepts RF energy and delivers oscillating
electric current to electronic equipment, and the transmitting antenna is fed
with electric current to generate RF field. They consist of metallic
conductors, electrically connected to transistor or receiver.
Anti Ferromagnetism
Phenomenon
of magnetic moment (spin moments) of neighboring atoms or ions aligned in
exactly opposite directions.
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