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
Resonance (Sound)
It
is the phenomenon in which if one of the two bodies of the same natural
frequency is set into vibration, the other body also vibrates with larger
amplitude under the influence of the first body.
Resonance Absorption (Dielectric)
Dispersion
arising during transition from full atomic polarization at radio frequencies to
negligible atomic polarization at optical frequency is called as resonance
absorption.
Resonant
Frequency (Electricity)
It is the frequency of alternating current
at which impedance of a series LCR circuit becomes least.
Rest
Mass
When the object
has zero speed, it is said to be at rest (as observed by us or by someone
accompanying the object). The mass possessed by body at rest is said to be rest
mass. It is an intrinsic property of object.
Restoring
Force
The force which acts on the particle in a
direction opposite to direction of its displacement.
Resultant
Force
The final force which acts on an object
when multiple forces acts on the body.
Reverberation
Period
When after the
principal sound stops, the intensity of sound remains one millionth part (or 10-6
th part) of its initial intensity i.e., the loudness of sound decreases
by 60db, is known as reverberation period.
Reverberation
The persistence of sound waves even after
source stopped emitting is known as “Reverberation”. The phenomenon normally
occurs in closed volumes.
Reverse
Bias
Biasing of PN diode in which p-portion is kept
at less potential in comparison to n-type. The diode under this bias is poorly
electrical conductive.
Reverse
Biased Diode
Configuration of P-N diode in which ‘P’
junction is applied low potential and ‘N’ junction is applied high potential.
Reversible
Cell
Cell which can be
brought back to original condition after cell is discharged by passing a
current through it in reverse direction.
Reversible
Change
Reversible
change is a change in which if a process is reversed by small changes in
external conditions, there is an exact repetition of all changes in reverse
path as they were in direct path, and there is no change in state of
surroundings and the system taking part in the process.
Conditions
of reversibility:
i)
There
must be complete absence of dissipation forces such as friction, viscosity etc.
ii)
The direct & reverse process must take
place infinitely slowly.
iii)
The
temperature of system must not differ appreciably from its surroundings.
Reversible
Process
If a process is carried out in such a way that
every moment the system departs only infitesimally from an equilibrium state, then that process is called reversible
process. At every instance, the system remains virtually in state of
equilibrium.
Reynolds
Number
Reynolds
number, in fluid mechanics, a criterion of whether fluid (liquid or gas)
flow is absolutely steady (streamlined, or laminar)
or on the average steady with small unsteady fluctuations (turbulent).
The
Reynolds number, abbreviated NRe or Re, has no dimensions. The concept was introduced
by George Gabriel Stokes in 1851, but the Reynolds number
is named after Osborne Reynolds (1842–1912),
who popularized its use in 1883.
Rheostat
Mechanical
arrangement containing continuous coiling of wire at one end and a wiper to
decide magnitude of resistance. It is variable resistance used for various
applications like regulating currents, check load & line regulations etc.
Richardson-Dushman
Equation
Owen
W. Richardson in 1928 received the noble prize in physics for his work and the
discovery of law governing the phenomenon thermionic emission. Dushman demonstrated
modern form of law governing the thermionic emission and law is now referred as
Richardson- Dushman equation. It expresses the relationship between the current
density ‘j’ in ampere per meter of electrons emitted from metal and absolute
temperature ‘T’ in Kelvin of metal as
j=AT2 e-eØ /kT
Where ‘A’ is Richardson constant with a theoretical
value of 1.2×106
A/m2/K2, and eØ
is work function of metal.
Rigid
Body
It is a body in
which the distances between the particles do not change as the body moves
about. Rigid body is an idealized concept, there is nothing really rigid
body.
Ripple
AC component
superimposes over DC
Rocket
Space craft which move with velocity enough to escape earth’s gravitational field with the help of its engines exhaust which gives thrust. Rocket engine works on action and reaction principle. They are used for carrying man made satellites in to space and put in required orbits around earth.
No comments:
Post a Comment