Measurement of Temperature

Measurements of Temperature is a physical quantity and hence, measurable. In fact in SI system, temperature is a fundamental physical quantity.

By our bodily sensation, we can say which object is hot and which is cold. But such a decision about temperature is not reliable. For example, place your right hand in hot water and left hand in cold water. After a few minutes, place both of your hands in water at room temperature. Now the same water appears cold for right hand and hot for left hand.

Measurement of temperature is a very important factor in various scientific experiments. The science of measurement of temperature is known as thermometry. The devices used to measure temperatures are known as thermometers

Heat and Temperature -

Heat energy is present in every object above absolute zero. How do we know that heat is present in every object? Temperature of the body is an indication.

(Absolute zero is the lowest temperature possible and is equal to -273^oC).

Are heat and temperature one and the same?

No. They are different. Heat is a form of energy and temperature represents the degree of hotness of a body. We can say, 'Heat is the cause and temperature is the effect'.

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Explain Capillary waves

Let us learn what is capillary waves,
A wave occurring at the interface between two fluids, such as the interface between air and water on oceans and lakes, in which the principal restoring force is controlled by surface tension.
A water wave of less than 1.7 centimeters. Also known as capillary ripple.

Surfaces of liquids are decorated with thermally activated capillary waves. Their amplitudes are on the order of angstroms. Many X-ray scattering experiments, which show the unambiguous fingerprints of capillary waves on liquid surfaces, have been performed in the past. These experiments, however, have tested the static time-averaged structure rather than the dynamics of the surface fluctuations. This is due to the major drawback that conventional X-ray sources are essentially incoherent, which renders the direct measurement of dynamics impossible. With high-brilliance third-generation sources it has become possible to obtain intense X-ray beams possessing a high degree of coherence. Such beams are produced by selecting the coherent part of the impinging radiation from an otherwise incoherent beam using micrometre-sized pinholes. These coherent beams make photon correlation spectroscopy with X-rays (XPCS) possible.
Hope the above explanation helped you.

ELASTIC BEHAVIOR OF MATERIALS

Let us study about elastic behavior of materials,
When a real material is studied at progressively diminishing scales, it is usually found to exhibit a
variation in properties from point to point. This variation is called structure. The term is often used with reference to a certain scale, e.g., atomic structure, microstructure, etc. The mechanical response of material to loading depends on its structure, and a large section of materials science is devoted to the analysis of this dependence. However, some fundamental aspects of mechanical behavior can be understood very well if the material is considered to be structureless,
a solid continuum. Solids respond to applied external loads by developing internal forces. If an imaginary section through the solid is considered, the components of internal force acting on a unit elemental area are called stresses.

Under the action of stresses solids deform, so that the distances between points change. However, provided the stresses are sufficiently small, the solid recovers its original shape and volume once the load is removed. This type of behavior is called elastic. Continuum elasticity considers the consequence of atomic interactions in solids, but disregards their nature. The
atomic aspects of elastic deformation are considered in Elastic BehaŠior of Materials: Physical Basis. Nonelastic behavior is manifested in residual deformation persisting after load removal, and often gives rise to residual stress. Under very low loads, deformation is found to be proportional to stress. The case of linear continuum elasticity is the main subject of this article. First, the foundations of stress and strain are laid out in the infinitesimal limit. Then simple forms of the elastic equations for isotropic bodies are introduced using
Lame!'s constants, as well as Young's modulus and Poisson's ratio.
Hope the above explanation helped you.

Accelaration due to gravity of the earth

Let us learn what is accelaration due to gravity of the earth,
The earth can be imagined to be a sphere made of a large number of concentric spherical shells
with the smallest one at the centre and the largest one at its surface. A point outside the
earth is obviously outside all the shells. Thus, all the shells exert a gravitational force at the
point outside just as if their masses are concentrated at their common centre according
to the result stated in the last section. The total mass of all the shells combined is just the mass
of the earth. Hence, at a point outside the earth, the gravitational force is just as if its entire mass
of the earth is concentrated at its center. For a point inside the earth, the situation is different. This is illustrated in Fig.The mass m is in a mine located at a depth d below the surface of the Earth of mass ME and radius RE. We treat the Earth to be spherically symmetric.
Again consider the earth to be made up of concentric shells as before and a point mass m situated at a distance r from the centre. The point P lies outside the sphere of radius r. For
the shells of radius greater than r, the point P lies inside. Hence according to result stated in
the last section, they exert no gravitational force on mass m kept at P. The shells with radius ≤ r
make up a sphere of radius r for which the point
P lies on the surface.
Hope the above explanation helped you,Now let us learn the laws of gravity.