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Using Sound To Measure Temperature
CHAPTER ONE -- [Total Page(s) 3]
Page 2 of 3
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1.0.BACKGROUND OF THE STUDY:
A temperature is an
objective comparative measure of hot or cold. It is measured by a
thermometer, which may work through the bulk behaviour of a thermometric
material, detection of thermal radiation , or particle kinetic energy
Several scales and units exist for measuring temperature, the most
common being Celsius (denoted °C; formerly called centigrade),
Fahrenheit (denoted °F), and, especially in science, Kelvin (denoted K).
The
coldest theoretical temperature is absolute zero, at which the thermal
motion in matter would be zero. However, an actual physical system or
object can never attain a temperature of absolute zero. Absolute zero is
denoted as 0 K on the Kelvin scale, −273.15 °C on the Celsius scale,
and −459.67 °F on the Fahrenheit scale.
The kinetic theory offers a
valuable but limited account of the behaviour of the materials of
macroscopic systems, especially of fluids. It indicates the absolute
temperature as proportional to the average kinetic energy of the random
microscopic motions of their constituent microscopic particles such as
electrons, atoms, and molecules.
Temperature is important in all
fields of natural science, including physics, geology, chemistry,
atmospheric sciences, medicine , and biology—as well as most aspects of
daily life. Many physical processes are affected by temperature, such as
physical properties of materials including the phase ( solid , liquid ,
gaseous or plasma), density , solubility, vapour pressure , electrical
conductivity rate and extent to which chemical reactions occur the
amount and properties of thermal radiation emitted from the surface of
an object speed of sound is a function of the square root of the
absolute temperature.
Temperature scales differ in two ways: the
point chosen as zero degrees, and the magnitudes of incremental units or
degrees on the scale.
The Celsius scale (°C) is used for common
temperature measurements in most of the world. It is an empirical scale.
It developed by a historical progress, which led to its zero point 0 °C
being defined by the freezing point of water, with additional degrees
defined so that 100 °C was the boiling point of water, both at sea-level
atmospheric pressure. Because of the 100 degree interval, it is called a
centigrade scale. [1] Since the standardization of the kelvin in the
International System of Units, it has subsequently been redefined in
terms of the equivalent fixing points on the Kelvin scale, and so that a
temperature increment of one degree Celsius is the same as an increment
of one kelvin, though they differ by an additive offset of 273.15.
The
United States commonly uses the Fahrenheit scale, on which water
freezes at 32 °F and boils at 212 °F at sea-level atmospheric pressure.
Many
scientific measurements use the kelvin temperature scale (unit symbol
K), named in honour of the Scottish physicist who first defined it. It
is a thermodynamic or absolute temperature scale. Its zero point, 0 K,
is defined to coincide with coldest physically-possible temperature
(called absolute zero). Its degrees are defined through thermodynamics.
The temperature of absolute zero occurs at 0 K = -273.15 °C (or −459.67
°F), and the freezing point of water at sea-level atmospheric pressure
occurs at 273.15 K = 0 °C.
The International System of Units (SI)
defines a scale and unit for the kelvin or thermodynamic temperature by
using the reliably reproducible temperature of the triple point of water
as a second reference point (the first reference point being 0 K at
absolute zero). The triple point is a singular state with its own unique
and invariant temperature and pressure, along with, for a fixed mass of
water in a vessel of fixed volume, an autonomically and stably
self-determining partition into three mutually contacting phases,
vapour, liquid, and solid, dynamically depending only on the total
internal energy of the mass of water. For historical reasons, the triple
point temperature of water is fixed at 273.16 units of the measurement
increment.
CHAPTER ONE -- [Total Page(s) 3]
Page 2 of 3
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ABSRACT - [ Total Page(s): 1 ]A method to measure the real time temperature distribution along an interferometer path based on the propagation of acoustic waves is presented. It exploits the high sensitivity of the speed of sound in air to the air temperature. In particular, it takes advantage of a special set-up where the generation of the acoustic waves is synchronous with the amplitude modulation of a laser source. A photodetector converts the laser light to an electronic signal considered as reference, while the incoming ... Continue reading---
