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12021 14115 3 Hours / 100 Marks Instructions – Seat No. (1) All Questions are Compulsory. (2) Answer each Section on separate answer sheet. (3) Answer each next main Question on a new page. (4) Illustrate your answers with neat sketches wherever necessary. (5) Figures to the right indicate full marks. (6) Assume suitable data, if necessary. (7) Use of Non-programmable Electronic Pocket Calculator is permissible. (8) Mobile Phone, Pager and any other Electronic Communication devices are not permissible in Examination Hall. Marks SECTION – I 1. Attempt any NINE of the following: 18 a) State the relation between electric field intensity and electric flux density. Give significance of each term involved. b) Why earth is considered at zero potential? c) For a silica optical fibre the refractive index of core layer is 1.56 and that of cladding is 1.35. Calculate the critical angle. P.T.O. 12021 [2] Marks d) State the conditions for total internal reflection. e) Draw energy band diagram for conductors and semiconductor. f) When a charge of 0.04 micro coulomb is given to a capacitor its potential is raised to 200 volts. Find its capacitance. g) What is the effect of temperature on the conductivity of semiconductor? h) Define the term. (i) Nanoscale (ii) Nanoparticles i) State coulomb’s inverse square law. j) Define capacitance. State its SI unit. k) Give any two applications of optical fibre. Attempt any FOUR of the following: 2. 16 a) Obtain an expression for intensity of electric field at a point in an electric field of charge Q coulomb, placed in a medium of dielectric constant K. b) Define electric lines of force. State its any three properties. c) A sphere of radius 20 cm is given a charge of 1600 microcoulomb and placed in air. Find the intensity of electric field: (i) at a point 60 cm from the centre of the sphere. (ii) at a point on the surface of the sphere. d) Two electric charges of 33 microcoulomb and –55 micro coulomb are situated 1.6 m apart in air. Determine the position of the point in between them where potential due to both charges is zero. e) Explain the propagation of light through a optical fibre. f) Define acceptance angle, critical angle numerical aperture. State formula to calculate numerical aperture. 12021 [3] Marks Attempt any FOUR of the following: 3. 16 a) Derive an expression for the capacitance of a parallel plate capacitor. b) Two condensers have an equivalent capacitance of 24 microfarad when connected in parallel and 2.25 microfarad when connected in series. Calculate the individual capacitance. c) Distinguish between P-type and N-type semiconductor. d) Give one application each of nanotechnology in electronics, automobile. e) Define forbidden energy gap. Draw energy band diagram for conductor semiconductor and insulators. f) Derive an expression for the resultant capacitance, when condensers are connected in series. P.T.O. 12021 [4] Marks SECTION – II 4. Attempt any NINE of the following: 18 a) What is buffer solution? Give types of buffer solutions. b) How batteries are classified? c) Define electrochemical cell and closed circuit voltage. d) How are the insulating materials classified? e) Define adhesives and write two examples. f) Name four important ores of copper with formula. g) Write two physical properties and two applications of Alluminium. h) Define immersed corrosion. Give one example. i) Which oxide film is protective against corrosion? Why? j) Why galvanized containers are not used for food storage? k) Write two types of stable oxide film. 5. Attempt any FOUR of the following: a) What is effect of dilution on specific conductivity? b) Explain the construction and working of Ni-Cd storage cell with neat labelled diagram. c) Draw a neat labelled diagram of H2-O2 fuel cell. Write electrode reaction. d) What are the advantages and limitations of fuel cell? e) Write two properties and applications of phenol formaldehyde and epoxy resin. f) What are ceramics? Give their classification on the basis of it’s uses. 16 12021 [5] Marks Attempt any FOUR of the following: 6. a) Explain the process of smelting of copper ore in the blast furnace. b) Describe electrolytic reduction of alumina. c) Write composition, properties and applications of following alloys: (i) Rose metal (ii) Tinmann’s solder. d) Define Sherardizing. State and explain the principle of Sherardizing. e) Name and explain the process of protecting steel article from corrosion by coating tin over it. f) Describe hydrogen evolution mechanism of immersed corrosion. 16