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Sunday, 27 October 2013

Electromagnetic waves and radiating systems - model question paper for B.Tech



1(a) Explain Ampere’s Force law. (4 Marks)
(b) Show that the capacitance of an isolated sphere of radius R is 4πε0R Farad. (6 Marks)
(c) What is Dirac Delta? Draw approximate form and symbolic representation. (6 Marks)
(d) Verify that the expression for the potential due to an electric dipole satisfies the Laplace equation. (4 Marks)
2 (a) Write Maxwell’s equations. (5 Marks)
(b) Explain linear, elliptical and circular polarization. (6 Marks)
(c) Write notes on surface impedance and skin effect. (4 Marks)
(d) Sketch the planes of zero magnetic field strength, zero EZ, and zero EY for the case of oblique reflection with E parallel to plane of incidence. (5 Marks)
3 (a) State and explain Poynting’s theorem. (6 Marks)
(b) Write a note on attenuation in parallel-plane guides. (6 Marks)
(c) What is attenuation factor? (4 Marks)
(d) Show that a coaxial line having an outer conductor of radius ‘b’ will have minimum attenuation when the radius ‘a’ of the inner conductor satisfies the ratio b/a=3.6 (4 Marks)
4(a) Explain Child-Langmuir law. (4 Marks)
(b) Write a note on frequency response of dielectric materials. (6 Marks)
(c) Deduce the expression for the power radiated through a spherical surface by the dipole of half-length H. (6 Marks)
(d) Determine the distance from a 60-cycle circuit where the radiation field ia almost equal to the induction field. (4 Marks)
5 (a) Explain Thevinin’s theorem. (4 Marks)
(b) What are the directional properties of dipole Antennas? (4 Marks)
(c) Write a note on practical antennas and methods of excitation. (8 Marks)
(d) A uniform cross section tower antenna is 400 ft high and 7 ft square. Determine the base impedance at a frequency of 1300 kHz. (4 marks)
6 (a) Explain Tchebyscheff distribution. (8 Marks)
(b) Design a six element broadside array having a spacing d=λ/2 between adjascent elements. The pattern is to be optimum, with the side-lobe level 20 db down. (6 Marks)
(c)Write a note on slotted cylinder antennas. (6 Marks)
7 (a) What are biconical antennas? Explain the two methods for the calculation of terminal impedance. (8 Marks)
(b) Write the expression for the reactance of a monopole antenna. Explain the terms. (4 Marks)
(c) Draw and explain average characteristic impedance for cylindrical antennas. (4 Marks)
(d) Using Schelkunoff’s method, calculate the input impedance of a uniform cross section tower antenna at 1300 kHz. The tower is 400 ft high and 6.5 ft square. The base-insulator capacitance is 30 pf. (4 Marks)
8 (a) What is antenna bandwidth? Explain. (4 Marks)
(b) What is LUHF? Mention any 3 factors on which it depends. (4 Marks)
(c) Explain Michelson-Morley experiment. (8 Marks)
(d) Derive electromagnetic relations from theory of special relativity. (4 Marks)

Aerodynamics-model question paper for B.Tech/M.Tech/PhD.



1 (a) Derive Archimedes principle using a body of general shape. (4 Marks)
(b) Prove that in a velocity field, the curl of the velocity is equal to the vorticity. (8 Marks)
(c) Write the continuity equation in terms of substantial derivative. ( 4 Marks)
(d) The velocity field is given by u = y/(x2+y2) and v = -x/(x2+y2) . Calculate the equation of the streamline passing through the point (0, 5). (4 Marks)
2 (a) Explain how Pitot tubes are used for the measurement of airspeed. (6 Marks)
(b) Write a note on Kutta-Joukowski theorem. (6 Marks)
(c) Explain double-surface airfoil. (4 marks)
(d) Consider an airfoil in a flow at standard sea level conditions with a freestream velocity of 50 m/s. At a given point on the airfoil, the pressure is 0.9×105 N/m2. Determine the velocity at this point. (4 Marks)
3 (a) What is elliptical lift distribution? (4 marks)
(b) A vortex filament of strength S assumes shape of closed circular loop of radius R. Obtain an expression for the velocity induced at the centre of the loop in terms of S and R. (6 Marks)
(c) Explain the variation of drag coefficient with Reynolds number for a sphere with the help of a graph. (6 Marks)
(d) Prove that three-dimensional source flow is irrotational. (4 Marks)
4 (a) Write a note on isentropic relations. (4 Marks)
(b) Show that total temperature is constant across a stationary normal shock wave. (6 Marks)
(c) Write and explain Rayleigh Pitot tube formula. (4 Marks)
(d) Consider a room with rectangular floor that is 5m by 7m and a 3.3 m high ceiling. The air pressure and temperature in the room are 1 atm and 250C respectively. Calculate the internal energy and enthalpy of the air in the room temp. (6 Marks)
5 (a) Write a note on supersonic nozzle flow with a normal shock inside the nozzle. (6 Marks)
(b) What are Prandtl-Meyer expansion waves? (4 Marks)
(c) Write a note on SCRAMjet engines. (4 Marks)
(d) An oblique shock wave has wave angle 300. The upstream flow Mach number is 2.4. Calculate the deflection angle of the flow, the pressure and temperature ratios across the shock wave and the Mach number behind the wave. (6 Marks)
6 (a) Define critical Mach number. How will you estimate critical Mach number? (6 Marks)
(b) Write a note on linearized supersonic flow. (6 Marks)
(c) Explain predictor-corrector process. (4 Marks)
(d) A flat plate at α = 200 is in a Mach 20 freestream. Calculate the lift and wave drag coefficients using Newtonian theory. (4 Marks)
7 (a) Deduce Naiver-Stokes equations for an unsteady, compressible, three dimensional viscous flow. (8 Marks)
(b) What is Couette flow? Explain. (4 Marks)
(c) What is Poiseuille flow? Explain. (4 Marks)
(d) Explain the terms adiabatic wall temperature and Reynolds analogy. (4 Marks)
8 (a) What are boundary layer equations? Explain the method of solving boundary layer equations. (8 Marks)
(b) What is stagnation region? Explain. (4 Marks)
(c) Write a note on Baldwin-Lomax turbulence model. (4 Marks)
(d) What is skin friction drag? Explain. (4 Marks)

Monday, 21 October 2013

Engineering electromagnetics - model question paper for B.Tech / M.Tech



1(a) Transform the vector B = y ax – x ay + z az into cylindrical co-ordinates. (4 Marks)
(b) Derive an expression for electric field due to an infinite sheet of electric charge. (6 Marks)
(c) Explain Gauss’s law. Mention one application. (6 Marks)
(d) Find div D at the origin if D = e-x sin y ax – e-x cos y ay + 2 Z az. (4 Marks)
2 (a) Write notes on potential gradient and electric field due to dipole. (8 Marks)
(b) Deduce a relation for the work done in moving a point charge in an electric field. (4 Marks)
(c) Write a note on ‘the method of images’. (4 Marks)
(d) The electron and hole mobilities of a semiconductor are 0.43 and 0.21 m2/volt.sec at a particular temperature. If the electron and hole concentrations are both 2.3× 1019 m-3, find the conductivity at this temperature.  (4 marks)
3 (a) What are the boundary conditions for perfect dielectric materials? (6 Marks)
(b) Deduce the capacitance of a two-wire line. (10 Marks)
(c) Determine the dielectric constant of a material in which the electric flux density is 4 times the polarization. (4 Marks)
4 (a) Derive Poisson’s and Laplace’s equations. (6 Marks)
(b) Explain how Laplace’s equation can be solved through numerical iteration. (8 Marks)
(c) The four sides of a square trough are held at potentials 0, 20, -30 and 60 volt. The highest and lowest potentials are kept on opposite sides. Determine the potential at the centre of the trough. (6 Marks)
5 (a) What is Ampere’s circuital law. (4 Marks)
(b) Write a note on Stoke’s theorem. (4 Marks)
(c) Differentiate between scalar and vector magnetic potentials. (8 Marks)
(d) A filamentary conductor is formed into an equilateral triangle with sides of length ‘l’ carrying current ‘I’. Determine the magnetic field intensity at the centre of the triangle. (4 Marks)
6 (a) Explain self inductance and mutual inductance. (6 Marks)
(b) What are retarded potentials? (4 Marks)
(c) Write Maxwell’s equations in point form and in integral form. (6 Marks)
(d) A ferrite material is operating in a linear mode with B = 0.05 T. If mr=50, calculate M, H and cm. (4 Marks)
7 (a) Write a note on lossless propagation of sinusoidal voltages. (6 Marks)
(b) What is skin effect? Derive a relation for skin depth. (6 Marks)
(c) Write a note on wave polarization. (4 Marks)
(d) A 50 Ω lossless transmission line is terminated by a load impedance, ZL = 50 – j75 Ω. If the incident power is 100 mW, find the power dissipated by the load.  (4 marks)
8(a) What is chromatic angular dispersion? (4 Marks)
(b) Write a note on planar dielectric waveguides. (6 marks)
(c) Write a note on radiation of electromagnetic energy from a simple dipole antenna. (6 Marks)
(d) An optical fiber link is known to have dispersion β2=20ps2/km. A Gaussian light pulse at the input of the fiber is of initial width T = 10 ps. Determine the width of the pulse at the fiber output if the fiber is 15 km long. (4 Marks)

Tuesday, 8 October 2013

Nanosensors and devices-model question paper for B.Tech/M.Tech Nanotechnology



1(a) What is a vacuum sensor? (4 Marks)
(b) What are photoelectric switches? (4 Marks)
(c) Explain with the help of a neat sketch, the working of a pressure sensor. (6 Marks)
(d) Distinguish between venturi tube and dall tube. (6 Marks)
2(a) What is electroluminescence? (4 Marks)
(b) Write notes on magneto-optic kerr effect and Pockel’s effect. (8 Marks)
(c) Write notes on photoresistors and phototransistors. (8 Marks)
3(a) What is a calomel electrode? Explain its relevance in nanosensors. (6 Marks)
(b) Mention and explain some medically significant measurands. (8 Marks)
(c) Explain the working of a biopotential sensor. (6 Marks)
4(a) Distinguish between Coated-wire electrodes and polymer-membrane electrodes. (8 Marks)
(b) Write notes on cyclic voltammetry and Hydrodynamic amperometry. (8 Marks)
(c) Explain the working of Reagent-mediated sensors. (4 Marks)
5(a) Explain the working of a blood glucose sensor. (10 Marks)
(b) Distinguish between chemoreceptor and barroreceptor. (10 Marks)
6(a) Write a detailed note on BIA core system. (10 Marks)
(b) Write a note on applications of biosensor based instruments for the bioprocess industry. (10 Marks)
7 (a) What is AMR effect? (4 Marks)
(b) Write a note on flipping. (6 Marks)
(c) Distinguish between dipole Plasmon resonance and quadrupole Plasmon resonance. (6 Marks)
(d) Write a note on spin polarized tunneling in nanostructures. (4 Marks)
8(a) Explain how proteins are used as nanodevices. (4 Marks)
(b) What are nanostructured biocompartments? (6 Marks)
(c) Write a note on DNA Sequencing with Nanopores. (6 Marks)
(d) Explain charge-transfer mechanisms- charge-tunneling and thermal-hopping. (4 Marks)