S
 Saturation Vapor pressure: The maximum amount of humidity which air can hold, at a particular temperature is defined by so called saturation water vapor pressure. Sievert: Unit of dose equivalent when dose ‘D’ is measured in Grays. Specific gravity of fluid: It is the ratio of weight of unit volume of fluid to unit volume of an equal volume of standard fluid, taken as water at 4 oC. Skin effect: When an alternating current of high frequency flows through the conductor, current density is not uniform throughout the crossectional area. Current density is more near the surface than inside the conductor. High frequency alternating current is confined to surface layer. The phenomenon is called as “skin effect”. Snell’s law: An empirical relationship formulated by willeboard snell around 1621 as per which Sin (angle of incidence)/sin(angle of refraction) = refractive index(medium) Spectrum: It is colored pattern obtained on screen after dispersion of light. Sputtering: The phenomenon of ejection or removal of atoms from target material by bombardment with high energetic particles. Straggling: Phenomenon in which identical charged particles, all having initial velocity do not have same range. The phenomenon occurs due to density inhomogenity in absorbing material. Superconductor: They are metals which when cooled below certain temperature called as critical temperature(usually few degrees above absolute zero) suddenly lose all traces of electrical resistance. Specific heat: Amount of heat required to raise the temperature of unit mass of material through one Kelvin .  C = Q/ M∆T; Q->heat required to raise temperature of mass M;   ∆T -> raise in temperature Specific heat at constant volume: Amount of heat required to raise the temperature of 1 mole of gas by 1oC at a constant volume. Specific heat at constant pressure: Amount of heat required to raise the temperature of 1 mole of gas by 1oC at a constant pressure. Stefan’s Boltzmann law: Total amount of radiant energy emitted by a black body per second per unit area is directly proportional to fourth power of its absolute temperature. E α T4; E = σ T4; σ is stefans constant. Saturation vapor pressure: The maximum amount of humidity which air can hold, at a particular temperature is defined by so called saturation water vapor pressure. Sievert: Unit of dose equivalent when dose ‘D’ is measured in Grays. Schottky defect: The formation of vacancies in Ionic crystals for charge neutrality is called Schottky defect. Skin depth: The depth inside the conductor at which the amplitude of electromagnetic decreases by a factor 1/e. It is measure of depth to which an Electromagnetic wave penetrates. Skin effect: When an alternating current of high frequency flows through the conductor, current density is not uniform throughout the crossectional area. Current density is more near the surface than inside the conductor. High frequency alternating current is confined to surface layer. The phenomenon is called “skin effect”. Sputtering: The process in which a surface is bombarded with energetic particle to cause ejection of surface atoms. The technique is used to make thin films on a substrate. Simple Harmonic Motion: The type of motion where the acceleration is directed towards a fixed point (the mean position of rest) and is proportional to displacement of vibrating particle. Specific Heat: Amount of heat required to raise temperature of unit mass of material through one Kelvin. Stefan’s-Boltzmann law: Total amount of radiant energy (E) emitted by a black body per second per unit area is directly proportional to fourth power of its absolute temperature (T). E a T4 à E = sT4; where s is Stefans Constant.Sphere of influence: A sphere drawn with a molecule as centre and molecular range as radius is called sphere of influence. Surface energy: The total energy involved in the formation of liquid surface is sum of potential energy due to mechanical work done and heat energy absorbed from the surroundings. The total energy per unit surface area is called surface energy. Simple pendulum: An arrangement of a heavy particle suspended by means of a weightless inextensible, flexible string from a rigid support making simple harmonic oscillation about mean position. Soldering: The American welding society defines soldering as metal coalescence below 800oF. Soldering is a process in which two adjoining metal surfaces are bonded by means of wetting the metal surfaces completely with molten filler material. Single Crystal: A crystal in which there is periodic arrangement and repeated arrangement of atoms exists throughout the crystal without any disturbance. All unit cells interlock in same fashion and have same orientation. Secondary bonds: Inter atomic and inter molecular bonds that are relatively weak and for which bonding energies are relatively small. Normally atomic or molecular dipoles are involved. Self diffusion: Atomic migration in pure metals. Shear: A force applied so as to cause or tend to cause two adjacent parts of same body to slide relative to each other in a direction parallel to their plane of contact. Softening point (glass): The maximum temperature at which a glass piece may be handled without permanent deformation; this corresponds to a viscosity of approximately 4x106 Pa.Sec Soft magnetic material: A ferromagnetic or ferrimagnetic material having small B vs H hysteresis loop, which may be magnetized and demagnetized with relative ease. Solubility limit: The maximum concentration of solute that may be added without forming a new phase. Specific strength: The ratio of tensile strength to specific gravity for a material. Steady state diffusion: The diffusion condition for which there is no net accumulation or depletion of diffusing species. The diffusion flux is independent of time. Strain (engineering): The change in gauge length of a specimen (in the direction of an applied stress) divided by its original gauge length. Structure: The arrangement of internal components of matter: electron structure (on a subatomic level), crystal structure (on an atomic level) and microstructure (on a microscopic level). Super cooling: Cooling to below a phase transition temperature without the occurrence of transformation. Super heating: Heating to above a phase transition temperature without occurrence of transformation. Spectral emissive power: The amount of radiant energy emitted in a range of unit wavelength at a wavelength ‘λ’ per second per unit area of a surface is called spectral emissive power at wavelength ‘λ’’of that surface. Spectral energy density: The radiant energy enclosed per unit volume in a unit wavelength range for a particular wavelength is called spectral energy density. Stefan’s law: The radiant energy emitted per second per unit area by a perfectly black body is directly proportional to the fourth power of the absolute temperature of the body. Stefan – Boltzmann’s law: Loss of heat per second from unit surface area of a black body at an absolute temperature ‘T’ surrounded by atmosphere at an absolute temperature ‘To’ is directly proportional to difference in fourth power of absolute temperature of that body and surrounding atmosphere. Solar constant: It is the amount of radiant energy received from the sun by the earth per unit area per unit time normally at the mean distance of earth from the sun. The numerical value is 1.388 x 103 Wm2. Satellite: These are natural or artificial bodies revolving around a planet under its gravitational attraction.Shearing strain: It is the ration of relative displacement between two layers of the body to the normal distance between those two layers. It can be expressed as the angle through which line originally normal to the field surface si Strain energy: When a body is deformed, the work done is stored in the form of potential energy in the body. This potential energy is called strain energy. Statistical Mechanics: It is the branch of science which establishes the interpretation of macroscopic behavior of system in tems of its microscopic properties. It doesn’t deal with motion of each particle but it takes into account the average or most probable properties of system without going into interior details of characteristics of its constituents. The larger is the number of particles in physical system considered, the more nearly correct are statistical predictions.   Self induction: The property of the circuit by virtue of which any change in current in it and hence change in magnetic flux in it induces an emf in it called self induction. Strange particles: Kaons(K-mesona) and hyperons are known as strange particles. They are produced in strong interactions but they decay slowly and hence called as strange particles. Silsbee effect: If the magnetic field produced by current carrying super conductors exceeds critical value, the material loses superconductivity and becomes normal. This phenomenon is called Silsbee effect named after its discoverer.