Al- Najah National University

1. Refractive index Refractive index • Al-Najah National University • Science College • (Electronic Physics Department ) Spesific gravity ,refractive index and vescosity of liquieds Prepared by : AlaaNajjar D.r:- IssamRashed

2. Our intent is to present some proprities of liquieds, spesificgravity,refractive index and vescosity of liquieds. They influence the mass and heat transfer, also influences the kinetics of phase separation processes. Affected by many other parameter like temperature and pressure , Finally mention some common application. Introduction

3. Spesific gravity

4. Specific gravity is the ratio of the density of a substance to the density (mass of the same unit volume) of a reference substance. The reference substance is nearly always water for liquids or air for gases.. What is the spesific gravity?

5. Temperature and pressure must be specified for both the sample and the reference. Pressure is nearly always 1 atm equal to 101.325 kPa. Temperatures for both sample and reference vary from industry to industry

6. Specific gravity is commonly used in industry as a simple means of obtaining information about the concentration of solutions of various materials such as brines, hydrocarbons, sugar solutions (syrups, juices, honeys, etc.) and acids. It used in

7. True specific gravity can be expressed mathematically as: Where is the density of the sample and is the density of water

8. Specific gravity can be measured in a number of ways. The following illustration involving the use of the pycnometer is instructive. A pycnometer is simply a bottle which can be precisely filled to a specific, but not necessarily accurately known volume, . Placed upon a balance of some sort it will exert a force . Measurement

9. Examples Material Balsa wood • Oak wood • Ethanol • Water • Table salt • Aluminium • Iron • Copper • Lead • Mercury • Depleted uranium • Gold • Osmium Specific Gravity • 0.2 • 0.75 • 0.78 • 1 • 2.17 • 2.7 • 7.87 • 8.96 • 11.35 • 13.56 • 19.1 • 19.3 • 22.59

10. Refractive index

11. In optics the refractive index or index of refractionn of a substance (optical medium) is a dimensionless number that describes how light, or any other radiation, propagates through that medium. It is defined as What is the refractive index?

12. The historically first occurrence of the refractive index was in Snell's law of refraction, n1sinθ1= n2sinθ2, where θ1 and θ2 are the angles of incidence of a ray crossing the interface between two media with refractive indices n1 and n2. History

13. Refraction, critical angle and reflection of light at the interface between two media.

14. The strong electric field of high intensity light (such as output of a laser) may cause a medium's refractive index to vary as the light passes through it, giving rise to nonlinear optics. If the index varies quadratically with the field (linearly with the intensity), it is called the optical Kerr effect and causes phenomena such as self-focusing and self-phase modulation..

15. If the index varies linearly with the field (which is only possible in materials that do not possess inversion symmetry), it is known as the Pockels effect

16. Wavefronts from a point source in the context of Snell's law. The region below the gray line has a higher index of refraction, and so light traveling through it has a proportionally lower phase speed than in the region above it Applications

17. The refractive index of a material is the most important property of any optical system that uses refraction. It is used to calculate the focusing power of lenses, and the dispersive power of prisms. It can also be used as a useful tool to differentiate between different types of gemstone. conclosion

18. Vescosity of liquids

19. The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress. For liquids, it corresponds to the informal notion of "thickness". For example, honey has a higher viscosity than water.[1] What is vescosity?

20. Viscosity is due to friction between neighboring parcels of the fluid that are moving at different velocities. It causes by?

21. A fluid that has no resistance to shear stress is known as an ideal fluid. • In the real world, zero viscosity is observed only at very low temperatures, in super fluid. • positive viscosity(viscosity is very high)the fluid will seem to be a solid. • a liquid whose viscosity is less than that of water is known as a mobile liquid. • while a substance with a viscosity greater than water is simply called a viscous liquid

22. Dynamic (or Absolute) Viscosity: • The dynamic viscosity(η) of a fluid is a measure of the resistance it offers to relative shearing motion. • η= F/ [A×(u/h)] • η= τ /(u/h) ; N-s/m² • Kinematic Viscosity : • The kinematic viscosity(v) is defined as the ratio of absolute viscosity to the density of fluid. • ν= η/ρ ; m²/s where; ρ= density of fluid

23. Effects of temperature:

24. Selection of lubricants for various purpose: • we can choose an optimum range of viscosity for engine oil. • In pumping operation. • for high viscous fluid high power will require. for low viscous fluid low power will require. • In making of blend fuel. • In the operation of coating and printing. Applications

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