OPTICAL FIBRE

OPTICAL FIBRE

• optical fibre is device which is used to conduct a light along any curved path.it works on the principle of total internal reflection.

• construction:optical consists of large no of fibre (strand)of fine quality glass (quartz)whose RI is 1-7 \
• each fibre is coated with thin layer (oladding) of material (glass of plastic) of RI 1.5
• thus core of this fibre is optically denser than outer layer 
• the fibre is very thin (diameter 10 raised -14)

DISPERSION OF LIGHT IN PRISM

DISPERSION OF LIGHT IN PRISM

• light travels in the form of waves,
• white light is composed of waves of diffrent wavelengths.
• the different colours of light are due to different wavelengh.
• red colour has maximum wavelength while violet has minimum.
• because of this the refractive index of the material for violet is greater than red,
• rays of different colour are deviated through prism.
• this seperation of colours gives rise to dispersion of light.

BASIC CONCEPT OF CHEMISTRY

BASIC CONCEPT OF CHEMISTRY

General topics:

The concept of atoms and molecules;
Dalton's atomic theory;
Mole concept;
Chemical formulae;
Balanced chemical equations;
Calculations (based on mole concept) involving common oxidation-reduction, neutralisation, and displacement reactions;
Concentration in terms of mole fraction, molarity, molality and normality.
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Stochiometric coefficients or numbers: The numbers which appear before the chemical symbols in a chemical equation.

Chemical equation gives information about moles of various reactants and products. Hence molar masses involved in the reaction and molar masses of products.

Mass percentage of substance in a system

Mole fraction of a substance in a system

Molarity = Amount of a substance (in mol)/Volume of solution expressed in dm^3
It is applicable to solutions only.

The unit of molarity is mol dm^-3. It is commonly abbreviated by the symbol M and is spelled as molar.

Molality = Amount of a a substance (in mol)/Mass of solvent expressed in kg
It is also applicable to solutions only

CONCEPT OF EQUIVALENT
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"One equivalent of a substance in a reaction is defined as the amount of substance which reacts or liberates 1 mol of electrons (or H^+ or OH^- ions).