Practical/Laboratory Manual Physics Class XII based on NCERT guidelines by Dr. Sunita Bhagia & Megha Bansal

Practical/Laboratory Manual Physics Class XII based on NCERT guidelines by Dr. Sunita Bhagia & Megha Bansal
Author: Dr. J. P. Goel
Publisher: SBPD Publications
Total Pages: 71
Release: 2020-06-24
Genre: Science
ISBN:

SECTION : A EXPERIMENTS 1.To determine resistance per cm of a given wire by plotting a graph for potential difference versus current, 2.To find resistance of a given wire using meter bridge and hence determine the specifi resistance (Resistivity) of its material, 3.To verify the laws of combination (Series/Parallel) of resistance using ameter bridge, 4.To compare the e.m.f. of two given primary cells using potentiometer, 5.To determine the internal resistance of a given primary cell (e.g. Leclanche cell) using potentiometer, 6.To determine the resistance of a galvanometer by half deflection method and to find its figure of merit. 7 A. To convert a given galvanometer (of known resistance and figure of merit) into an ammeter of desired range and to verify the same, 7.B.To convert a given galvanometer (of known resistance and figure of merit) into a voltmeter of desired range and to verify the same. 8.To find the frequency of AC mains with a sonometer and horse-shoe magnet. SECTION : B EXPERIMENTS 1.To find the value of v for different values of u in case of a concave mirror and to find the focal length, 2.To find the focal length of a convex lens by plotting graph between u and v or 1/u and 1/v. 3.To find the focal length of a convex mirror, using a convex lens.4.To find the focal length of a concave lens, using a convex lens. 5. To determine the angle of minimum deviation for a given prism by plotting a graph between the angle of incidence and angle of deviation, 6. To determine refractive index of a glass slab using a travelling microscope, 7.To find the refractive index of a liquid by using a convex lens and a plane mirror, 8.To draw I-V characteristics curve of a p-n function in forward bias and reverse bias, 9.To draw the characteristics curve of a zener diode and to determine its reverse break down voltage, 10.To study the characteristics of a common-emitter n-p-n or p-n-p transistor and to find out the values of current and voltage gains. SECTION : A ACTIVITIES 1.To measure the resistance and impedance of an inductor with or without iron core, 2.To measure resistance voltage (AC/DC), current (AC) and check continuity of given circuit using multimeter, 3. To assemble a household circuit comprising of three bulbs, three (on/off)switches, a fuse and a power source. 4.To assemble the components of a given electrical circuit. 5.To study the variation in potential drop with length of a wire for a steady current, 6.To draw the diagram of a given open circuit comprising atleast a battery, resistor/rheostat, key ammeter and voltmeter. Make the components that are not connected in proper order and correct the circuit and also the circuit diagram. SECTION : B ACTIVITIES 1.To study effect of intensity of light (by varying distance of the source) on an LDR (Light Depending Resistor), 2.To identify a diode, a LED, a transistor, an IC, a resistor and a capacitor from mixed collection of such items, 3. Use a multimeter to : (i) identify the transistor, (ii) distinguish between n-p-n and p-n-p type transistor, (iii) see the unidirectional flow of current in case of a diode and a LED, (iv) Check whether a given electronic components (e.g diode, transistor or IC) is in working order, 4.To observe refraction and lateral deviation of a beam of light incident obliquely on a glass slab, 5.To observe polarisation of light using two polaroids, 6. To observe diffraction of light due to a thin slit, 7.To study the nature and size of the image formed by : (i) convex lens, (ii) concave mirror on a screen by using candle and a screen for different distance of the candle from the lens/mirror, 8.To obtain a lens combination with the specified focal length by using two lenses from the given set of lenses. SUGGESTED INVESTIGATORY PROJECT 1.To Study Verious factors on which the Internal Resistance/EMF of a cell depends, 2.To study the variations in current following in a circuit containing L.D.R. because of variation. (a) In the power of incomdescent lamp used to illum inate the L.D.R. Keeping all the lamps in fixed position (b) In the Distance of a in condescent lamp (of fixed power) used to illum inate the L.D.R. 3. To find the refractive indeces of (a) Water (b) Oil (Transparent) using a plane mirror, an equiconvex lens (made from a glass of known refractive index) and an adjustable object needle, 4. To design an appropriate logic gate combination for a given truth table. 5. To investigate the relation between the ratio of : (i) Output and Input voltage (ii) Number of turms in secondary coils and primary coils of a self designed transformer. 6.To Investigate the dependence of angle of deviation on the angle of incidence, using a hollow prism filled one by with different transparent fluids, 7.To Estimate the charge induced on each one of the two identical styrofoam balls suspended in a vertical plane by making use of coulomob’s Law :, 8.To study the factors on which the self inductance of a coil depends by observing the effect of this coil, when put in series with a resistor (bulb) in a circuit fed up by an a.c. source of adjustable frequency, 9.To study the earth’s magnetic field using a tangent galvanometer. APPENDIX Some Important Tables of Physical Constants Logarithmic and other Tables

Practical/Laboratory Manual Physics Class - 12

Practical/Laboratory Manual Physics Class - 12
Author: Er. Meera Goyal
Publisher: SBPD Publications
Total Pages: 121
Release: 2023-04-30
Genre: Science
ISBN:

Sections : A 1. Experiments, 2. Activities, Sections : B 1. Experiments, 2. Activities, 3. Suggested Investigatory, 4. Project Work

Practical/Laboratory Manual Physics Class XI based on NCERT guidelines by Dr. J. P. Goel & Er. Meera Goyal

Practical/Laboratory Manual Physics Class XI based on NCERT guidelines by Dr. J. P. Goel & Er. Meera Goyal
Author: Dr. J. P. Goel
Publisher: SBPD Publications
Total Pages: 57
Release: 2020-06-26
Genre: Bibles
ISBN:

EXPERIMENTS 1.Measurement of Length 1.To measure the diameter of a small spherical/cylindrical body by using a vernier callipers, 2. To measure the dimensions of a given regular body of known mass, using vernier callipers and hence find its density, 3. To measure the internal diameter and depth of a given cylindrical vessel (say calorimeter/beaker) by using vernier callipers and hence find its internal volume (i.e., capacity) Viva-voce 2. Screw Gauge/Micrometer 4.To determine the diameter of a given wire using a screw gauge and find its volume, 5. To find the thickness of a given sheet with the help of screw gauge, 6.To measure the volume of an irregular lamina by using a screw gauge Viva-voce 3. Spherometer 7.To measure the radius of curvature of a given spherical surface (convex lens) by using a spherometer Viva-voce 4.Mass and Weight 8.To determine the mass of two different objects using a beam balance Viva-voce 5.Parallelogram Law of Vectors 9.To find the weight of a given body using parallelogram law of vectors Viva-voce 6.Simple Pendulum (Measurement of Time) 10.Using a simple pendulum, plot L–T and L–T2 graphs. Hence find the effective length of a second's pendulum, using appropriate graphs Viva-voce 7. Friction 11.To study the relationship between force of limiting friction and normal reaction and to find the coefficient of friction between a block and a horizontal surface, Viva-voce 8. Motion of a Body Along an Inclined Plane 12. To find the downward force along an inclined plane, acting on a roller due to gravitational pull of the earth and study its relationship with the angle of inclination by plotting graph between force and sin Viva-voce SECTION : B EXPERIMENTS 1.Elasticity 1.To determine the Young's modulus of elasticity of the material of the wire, using Searle's apparatus Viva-voce 2.Spring Constant 2.To find the spring constant of a helical spring by plotting load-extension graph Viva-voce 3. Boyle's Gas Law 3.To study the variation in volume with pressure for a sample of air constant temperature by plotting graphs between P and V and between P and 1/V 18 Viva-voce 4. Surface Tension 4.To determine the surface tension of water by capillary rise method Viva-voce 5.Viscosity 5.To determine the co-effective of viscosity of given liquid by measuring the terminal velocity of a given spherical body in it Viva-voce 6.Newton's Law of Cooling 6.To study the relationship between temperature of a hot body and time by plotting a cooling curv Viva-voce 7.Vibrations of Strings 7. To study the relation between frequency and length for a given wire under constant tension using a sonometer Viva-voce 8.To study the relation between the length of a given wire and tension for constant frequency using sonometer Viva-voce 8.Vibrations of Air Columns 9.To find the velocity of sound in air at room temperature using a resonance tube by two resonance position Viva-voce 9.Specific Heat 10.To determine specific heat of a given solid by the method of mixture 11.To determine the specific heat of a given liquid by method of mixture Viva-voce SECTION : A ACTIVITIES 1.To make a paper scale of given least count e.g., 0.2 cm, 0.5 cm and use it to measure the length of a given object. 2.To determine the mass of a given body using a metre scale and by applying principle of moments. Viva-voce 3.To plot a graph for a given set of data using proper choice of scales and error bars. Viva-voce 4.To measure the force of limiting friction for rolling of a roller on horizontal plane. Viva-voce 5.To study the variation in the range of a jet of water with angle of projection. Viva-voce 6.To study the conservation of energy of a ball rolling down on inclined plane (using a double inclined plane). Viva-voce 7. To study dissipation of energy of a simple pendulum by plotting a graph between square of amplitude and time. Viva-voce SECTION : B ACTIVITIES 1.To observe the change of the state and plot a cooling curve for molten wax. Viva-voce 2.To observe and explain the effect of heating on a bimetallic strip. Viva-voce 3.To note the change in level of liquid in a container on heating and interprect the observations. Viva-voce 4.To study the effect of detergent in surface tension by observing capillary rise. Viva-voce 5.To study the factors affecting the rate of loss of heat of a liquid. Viva-voce 6.To study the effect of load on depression of a suitably clamped meter scale loaded (i) at itsend (ii) in the middle. Viva-voce 7.To observe the decrease in pressure with the increase in velocity of the fluid. Viva-voce APPENDIX Some Important Tables of Physical Constants Log-Antilog and other Tables

Practical/Laboratory Manual Science Class X based on NCERT guidelines by Dr. J. P. Goel, Dr. S. C. Rastogi, Dr. Sunita Bhagia & Er. Meera Goyal

Practical/Laboratory Manual Science Class X based on NCERT guidelines by Dr. J. P. Goel, Dr. S. C. Rastogi, Dr. Sunita Bhagia & Er. Meera Goyal
Author: Dr. J. P. Goel
Publisher: SBPD Publications
Total Pages: 21
Release: 2020-06-26
Genre: Science
ISBN: 9389356296

Physics : 1.To determine the focal length of concave mirror, 2. To find the focal length of convex lens by two pin method, 3. To find the image distance for varying object distances in case of a convex lens and drawing corresponding ray diagrams to show the nature of image formed, 4.To trace the path of the rays of light through a glass prism, 5.To trace the path of a ray of light passing through a rectangular glass slab for difference angles of incidence. 6.To study the dependence of potential difference (V) across a resistor on the current (I) passing through it and determine its resistance. Also plotting a graph between V and I.7.To determine the equivalent resistance of two resistors when connected in series and parallel Chemistry : 8.To find the pH of the following samples by using pH paper universal indicator, 9.To studying the properties of a base (dil. NaOH Solution) and Acid (HCl) by their reaction with : (a) Litmus solution (Blue/Red), (b) Zinc metal, (c) Solid sodium carbonate, 10.To perform and observe the following reactions and to classify them into (a) Combination reaction, (b) Decomposition reaction, (c) Displacement reaction, (d) Double displacement reaction : (i) Action of water on quick lime, (ii) Action of heat on ferrous sulphate crystals, (iii) Iron nails kept in copper sulphate solution, (iv) Reaction between sodium sulphate and barium chloride solutions.11.To observe the action of Zn, Fe, Cu and Al on the following salt solutions : (a) ZnSO4 (aq.), (b) FeSO4 (aq.), (c) CuSO4 (aq.), (d) Al2 (SO4)3 (aq.). Based on the above result to arrange Zn, Fe, Cu and Al (metals) in the decreasing order or reactivity,12.To study the following properties of acetic acid (ethanoic acid) : (i) Odour, (ii) Solubility in water, (iii) Effect on litmus, (iv) Reaction with sodium hydrogen carbonate. 13.To study the comparative cleaning capacity of a sample of soap in soft and hard water. Biology : 14.To study stomata by preparing a temporary mount of a leaf peel. 15. To show experimentally that carbon dioxide (CO2) is given out during aerobic respiration, 16. To study (A) Binary fission in Amoeba and (B) Budding in yeast with the help of prepared slides, 17.To identify the different parts of an embryo of a dicot seed (pea, gram or red kidney beans.)

Practical/Laboratory Manual Science Class IX based on NCERT guidelines by Dr. J. P. Goel, Dr. S. C. Rastogi, Dr. Sunita Bhagia & Er. Meera Goyal

Practical/Laboratory Manual Science Class IX based on NCERT guidelines by Dr. J. P. Goel, Dr. S. C. Rastogi, Dr. Sunita Bhagia & Er. Meera Goyal
Author: Dr. J. P. Goel
Publisher: SBPD Publications
Total Pages: 33
Release: 2020-06-26
Genre: Science
ISBN: 9389356342

Physics : 1.To determine the focal length of concave mirror, 2. To find the focal length of convex lens by two pin method, 3. To find the image distance for varying object distances in case of a convex lens and drawing corresponding ray diagrams to show the nature of image formed, 4.To trace the path of the rays of light through a glass prism, 5.To trace the path of a ray of light passing through a rectangular glass slab for difference angles of incidence. 6.To study the dependence of potential difference (V) across a resistor on the current (I) passing through it and determine its resistance. Also plotting a graph between V and I.7.To determine the equivalent resistance of two resistors when connected in series and parallel Chemistry : 8.To find the pH of the following samples by using pH paper universal indicator, 9.To studying the properties of a base (dil. NaOH Solution) and Acid (HCl) by their reaction with : (a) Litmus solution (Blue/Red), (b) Zinc metal, (c) Solid sodium carbonate, 10.To perform and observe the following reactions and to classify them into (a) Combination reaction, (b) Decomposition reaction, (c) Displacement reaction, (d) Double displacement reaction : (i) Action of water on quick lime, (ii) Action of heat on ferrous sulphate crystals, (iii) Iron nails kept in copper sulphate solution, (iv) Reaction between sodium sulphate and barium chloride solutions. 11.To observe the action of Zn, Fe, Cu and Al on the following salt solutions : (a) ZnSO4 (aq.), (b) FeSO4 (aq.), (c) CuSO4 (aq.), (d) Al2 (SO4)3 (aq.). Based on the above result to arrange Zn, Fe, Cu and Al (metals) in the decreasing order or reactivity,12.To study the following properties of acetic acid (ethanoic acid) : (i) Odour, (ii) Solubility in water, (iii) Effect on litmus, (iv) Reaction with sodium hydrogen carbonate. 13.To study the comparative cleaning capacity of a sample of soap in soft and hard water. Biology : 14.To study stomata by preparing a temporary mount of a leaf peel. 15.To show experimentally that carbon dioxide (CO2) is given out during aerobic respiration, 16. To study (A) Binary fission in Amoeba and (B) Budding in yeast with the help of prepared slides, 17.To identify the different parts of an embryo of a dicot seed (pea, gram or red kidney beans.)

Practical/Laboratory Manual Chemistry Class XI based on NCERT guidelines by Dr. S. C. Rastogi & Er. Meera Goyal

Practical/Laboratory Manual Chemistry Class XI based on NCERT guidelines by Dr. S. C. Rastogi & Er. Meera Goyal
Author: Dr. S. C. Rastogi
Publisher: SBPD Publications
Total Pages: 53
Release: 2020-06-23
Genre: Science
ISBN: 9389356407

An Excellent Book in Accordance with the latest syllabus for Class-11 Prescribed by CBSE/NCERT and Adopted by Various State Education Boards. (A) Basic Laboratory Techniques – 1. To cut a glass tube or glass rod, 2. To bend the glass rod at an angle, 3. To draw a glass jet from a glass tube, 4. To bore a cork and fit a glass tube into it. (B) Characterisation and Purification of Chemical Substances- 1. To determine the melting point of the given unknown organic compound and its identification (simple laboratory technique), 2. To determine the boiling point of a given liquid when available in small quantity (simple laboratory method), 3. To prepare crystals of pure potash alum [K2SO4.Al2(SO4)3.24H2O] from the given impure sample, 4. To prepare the pure crystals of copper sulphate from the given crude sample, 5. To prepare pure crystals of benzoic acid from a given impure sample. (C) Measurement of pH Values 1. To determine the pH value of vegetable juices, fruit juices, tap water and washing soda by using universal pH paper, 2. To determine and compare the pH values of solutions of strong acid (HCI) and weak acid (CH3COOH) of same concentration, 3. To study the pH change in the titration of strong base Vs. strong acid by using universal indicator paper, 4. To study the pH change by common ion (CH3COO– ion) in case of weak acid (CH3COOH), 5. To determine the change in pH value of weak base (NH4OH) in presence of a common ion (NH4+), (D) Chemical Equilibrium 1. To study the shift in equilibrium between ferric ions and thiocyanate ions by changing the concentrations of either of the ions, 2. To study the shift in equilibrium between [Co(H2O)6]2+ and Cl– ions by changing the concentrations of either of the ions, (E) Quantitative Analysis 1. To prepare M/10 oxalic acid solution by direct weighing method, 2.To prepare M/10 solution of sodium carbonate by direct weighing method, 3.To determine the strength of given solution of sodium hydroxide by titrating it against N/10 or M/20 solution of oxalic acid, 4.To determine the strength of a given solution of hydrochloric acid by titrating it against a standard N/10 or M/20 sodium carbonate solution, (F) Qualitative Analysis 1. Analysis of Anions, 2. Analysis of Cations (G) Detection of Elements in Organic Compounds 1.To detect the presence of nitrogen, sulphur and halogens in a given organic compound by Lassaigne’s test, 2. To detect the presence of nitrogen, sulphur and halogens in the given organic compound sample number .......... by Lassaigne’s test INVESTIGATORY PROJECTS (A) Checking of Bacterial Contamination in Water 1.To check the bacterial contamination in drinking water by testing sulphide ions (B) Methods of Water Purification 1.To purify water from suspended impurities by using sedimentation, 2. To purify water by boiling, 3.To purify water by distillation method, 4.To purify water by reverse osmosis technique. 5.To purify water by GAC method, 6.To purify water by bleach treatment, 7.To purify water by oxidising agent, 8.To purify water by ozone treatment method. (C) Water Analysis 1. To test the hardness of different water samples. (D) Foaming Capacity of Various Soaps 1.To compare the foaming capacity of different washing soaps, 2.To study the effect of addition of sodium carbonate on foaming capacity of washing soap (E) Tea Analysis 1. To study the acidity of different samples of tea leaves (tea) by using pH paper (F) Analysis of Fruits and Vegetable Juices 1. To analyse the fruit and vegetable juices for the constituent present in them (G) Rate of Evaporation 1. To study the rate of evaporation of different liquids (H) Effect of Acids and Bases on Tensile Strength of Fibres 1.To compare the tensile strength of natural fibres and synthetic fibres, 2.To study the effect of acids and bases on tensile strength of different fibres. Log & Antilog Table

Physics

Physics
Author: D. C. Upadhyay,
Publisher: SBPD Publications
Total Pages: 734
Release: 2016-12-17
Genre:
ISBN: 9351674088

Strictly according to the latest syllabus prescribed by Central Board of Secondary Education (CBSE), StateBoard and Navodaya, Kendriya Vidyalayas etc. following CBSE curriculum based on NCERT guidelines.

Chemistry Class XII For Madhya Pradesh Board by Dr. S C Rastogi, Er. Meera Goyal

Chemistry Class XII For Madhya Pradesh Board by Dr. S C Rastogi, Er. Meera Goyal
Author: Dr. S C Rastogi,
Publisher: SBPD Publications
Total Pages: 1025
Release: 2020-06-17
Genre: Science
ISBN: 9382883002

Syllabus : Unit I : Solid State Unit II : Solutions Unit III : Electrochemistry Unit IV : Chemical Kinetics Unit V : Surface Chemistry Unit VI : General Principles and Processes of Isolation of Elements Unit VII : “p”–Block Elements Unit VIII : “d” and “f” Block Elements Unit IX : Coordination Compounds Unit X : Haloalkanes and Haloarenes Unit XI : Alcohols, Phenols and Ethers Unit XII : Aldehydes, Ketones and Carboxylic Acids Unit XIII : Organic Compounds Containing Nitrogen Unit XIV : Biomolecules Unit XV : Polymers Unit XV : Polymers Unit XVI : Chemistry in Everyday Life Content : 1. Solid State 2. Solutions 3. Electro-Chemistry 4. Chemical Kinetics 5. Surface Chemistry 6. General Principles And Processes Of Isolation Of Elements 7. P-Block Elements 8. D-And F-Block Elements 9. Coordination Compounds And Organometallics 10. Haloalkanes And Haloarenes 11. Alcohols, Phenols And Ethers 12. Aldehydes Ketones And Carboxylic Acids 13. Organic Compounds Containing Nitrogen 14. Biomolecules 15. Polymers 16. Chemistry In Everyday Life Appendix : 1. Important Name Reactions And Process 2. Some Important Organic Conversions 3. Some Important Distinctions

Practical/Laboratory Manual Chemistry Class - XI

Practical/Laboratory Manual Chemistry Class - XI
Author: Er. Meera Goyal
Publisher: RAJEEV BANSAL
Total Pages: 95
Release: 2021-05-29
Genre: Science
ISBN: 9351679594

1.Basic Laboratory Techniques 1.To cut a glass tube or glass rod, 2.To bend the glass rod at an angle, 3.To draw a glass jet from a glass tube 4.To bore a cork and fit a glass tube into it Viva-Voce 2.Characterisation and Purification of Chemical Substances 1.To determine the melting point of the given unknown organic compound and its identification (simple laboratory technique) Viva-Voce 2.To determine the boiling point of a given liquid when available in small quantity (simple laboratory method) Viva-Voce 3.To prepare crystals of pure potash alum [K2SO4.Al2(SO4)3.24H2O] from the given impure sample 4.To prepare the pure crystals of copper sulphate from the given crude sample 5.To prepare pure crystals of benzoic acid from a given impure sample Viva-Voce 3.Measurement of pH Values 1.To determine the pH value of vegetable juices, fruit juices, tap water and washing soda by using universal pH paper 2.To determine and compare the pH values of solutions of strong acid (HCI) and weak acid (CH3COOH) of same concentration 3.To study the pH change in the titration of strong base Vs. strong acid by using universal indicator paper 4.To study the pH change by common ion (CH3COO– ion) in case of weak acid (CH3COOH) 5.To determine the change in pH value of weak base (NH4OH) in presence of a common ion (NH4+) Viva-Voce 4.Chemical Equilibrium 1 To study the shift in equilibrium between ferric ions and thiocyanate ions by changing the concentrations of either of the ions 2.To study the shift in equilibrium between [Co(H2O)6]2+ and Cl– ions by changing the concentrations of either of the ions Viva-Voce 5. Quantitative Analysis 1.To prepare M/10 oxalic acid solution by direct weighing method 2.To prepare M/10 solution of sodium carbonate by direct weighing method 3.To determine the strength of given solution of sodium hydroxide by titrating it against N/10 or M/20 solution of oxalic acid 4.To determine the strength of a given solution of hydrochloric acid by titrating it against a standard N/10 or M/20 sodium carbonate solution Viva-Voce 6.Qualitative Analysis Analysis of Anions Analysis of Cations Viva-Voce 7.Detection of Elements in Organic Compounds 1.To detect the presence of nitrogen, sulphur and halogens in a given organic compound by Lassaigne’s test 2.To detect the presence of nitrogen, sulphur and halogens in the given organic compound sample number .......... by Lassaigne’s test Viva-Voce INVESTIGATORY PROJECTS 1.Checking of Bacterial Contamination in Water 1.To check the bacterial contamination in drinking water by testing sulphide ions Viva-Voce 2. Methods of Water Purification 1.To purify water from suspended impurities by using sedimentation 2. To purify water by boiling 3. o purify water by distillation method 4. To purify water by reverse osmosis technique 5. To purify water by GAC method 6. To purify water by bleach treatment 7. To purify water by oxidising agent 8. To purify water by ozone treatment method Viva-Voce 3. Water Analysis 1.To test the hardness of different water samples Viva-Voce 4. Foaming Capacity of Various Soaps 1 .To compare the foaming capacity of different washing soaps 2. To study the effect of addition of sodium carbonate on foaming capacity of washing soap Viva-Voce 5. Tea Analysis 1.To study the acidity of different samples of tea leaves (tea) by using pH paper Viva-Voce 6.Analysis of Fruits and Vegetable Juices 1. To analysis the fruit and vegetable juices for the constituent present in them Viva-Voce 7. Rate of Evaporation 1. To study the rate of evaporation of different liquids lViva-Voce 8. Effect of Acids and Bases on Tensile Strength of Fibres 1.To compare the tensile strength of natural fibres and synthetic fibres 2.To study the effect of acids and bases on tensile strength of different fibres Viva-Voce