Third Semeter

END TERM EXAMINATIONTHIRD SEMESTER [B.TECH.] DECEMBER-2012

~Ip-a-'P-e-r-C-o-d-e-:-E-:r,-M-E-2-0-a---- Subject: Electronics ITime: a Hours Maximum Marks :75

r- Note: Attempt any five questions including Q.no.l which is compulsory.I Select one question from each unit.- ,

(Please write your Exam Roll No.) Exam Roll No .

Ql (a)

(b)

(c)(d)

(e)

Q2 (a)

.?:' (b)

Q3 (a)(b)

Draw the volt-ampere output characteristics of a BJT in CE and CB configurations,Indicate the various regions of operation. Define 'a' and 'W derive a relation betweenthem.Draw the circuit diagram of a basic CE, CB and CC amplifier. Discuss the salientfeatures of each type of amplifier.Discuss the 'Barkhauser Criterion' for self-sustained oscillations.Using an op-amp, make a circuit to implement: (Vj+V2)-(V3+V4)where VI, V2, V3andV4 are input voltages.Simplify the Boolean function using Karnaugh Map, F=x'yz+xy'z'+xyz+xyz'. (5x5=25)

UNIT. IDraw the circuit of a Full-wave rectifier. Derive ripple factor, maximum rectificationefficiency, % vOhage regulation and PIV for the diodes. (6.5)Explain the construction, symbol and VI-characteristics of a Silicon ControlledRectifier. (6)

Explain the difference in DC and AC load lines in a transistor amplifi<::r. (6)Show that the transistor shown in fig.l is operating in the active region of operation.(6.5)

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MNIT-IIQ4 (a) Using n-parameter model, derive the expressions for Av, Avs, Ar, AIS,Ri, Ro and Ro'

for a basic CE amplifier. (8.5)(b) Explain the difference in Emitter Follower and Darlington emitter follower. Show the

circuit diagram of both. (4)

Q5 (a) Draw and explain the working of a class-B push-pull amplifier and derive its powerconversion efficiency. (6.5)

(b) Derive the expression of the frequency of oscillation and condition for oscillation foranyone type of LC oscillator. (6)

UNIT-IIIQ6 (a) Draw the structure and explain the drain and transfer characteristics for-

(i) Depletion (ii) Enhancement MOSFET. (6.5)(b) Draw the circuit of an op-amp Integrator. Derive its transfer function. Show the

output response for (i) Square wave (ii) Square wave (iii) Step input. (6)

Q7 (a) Explain the construction, working and drain characteristics of an FET.(b) Draw the circuit of a Schmitt Trigger and explain its operation.

(6.5)(6)

UNIT-IVQ8 (a) List the different types of shift Register. Discuss the working of anyone type. (6.5)

(b) Draw the circuit of a 4-bit counter using D-flip flops. Explain its working showingthe tilling diagram. (6)

Q9 (a) Draw the logical diagram, symbol and truth table of 3 to 8 line decoder.(b) Write a brief note on different types of RAM's and ROM's.

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(6.5)(6)

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Exam Roll No................•......CDEND TERM EXAMINATION

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THIRD SEMEST_ER lB.TECI!.l-l?_I!;C~M~.E~R_-_2_0_1_2 --,l-p-a-p-e-r-C-o-d-e-:-E-T-M-E-2-0-S--- , ,__,_,'_'_"'__ .., , ..~f:lbject: Thermal Science ITime: 3 Hours Maximum Marks :7S

Note: Attempt all questions. Internal choice is indicated. Use 0/ steam Itables &Mollier diagram is permitted. I

Q1 (a) Explain intensive and extensive properties. (3)(b) Write steady flow energy equation for a open system and write the same for

throttling process. (3)(c) With the help of an example and proper diagram show equivalence of Kelvin

Planck and Clausius statements. (3)(d) Explain second law efficiency. (3)(e) What do you understand by saturation states? Show different saturation

states coming across while heating ice at -50C to super heated steam. (3)(f) Write physical significance of Gibbs and Helmholtz functions. (3)(g) Using P-V and T-S diagram show that diesel cycle is more efficient than that

of otto cycle for same maximum cycle temperature and heat input. (4)(h) With the help of T-S diagram, explain effect of Reheating in Rankine cycle. (3)

Q2 Derive equation for P.dv work for a polytropic process and for constant pressureprocess. Show the process P-v diagram. (12.5)

ORAir flow with steady state at a flow rate of 0.5kg/ s through an air compressor.Inlet velocity, pressure and specific volume are 7m/s, 1 bar and 0.9m3/kgrespectively and these parameters at outlet of the compressor are 4m/s, 7 barand 0.15m3/kg respectively. The difference in internal energy between outletand inlet is 90kJ /kg. The cooling arrangement made in the compressor absorbs60W of energy. Calculate power required to drive the compressor and crosssectional areas at inlet and outlet. (12.5)

Q3 What do you understand available energy? Derive expression for loss ofavailable energy due to heat transfer through a finite temperature difference. (12.5)

ORA system having heat capacity at constant volume, Cv=A'f2,where A=0.043J /K3,is originally at 200K and a thermal reservoir at lOOK. Determine maximumamount of work that can be recovered as the system is cooled down to thereservoir's temperature. (12.5)

Q4 Derive Maxwell's relations of thermodynamics. (12.5)OR

With the help of following data taken from separating and throttlingcalorimeter, find the quality of steam flowing in the pipe:- (12.5)(a) Pressure in pipe line=1.6MPa,(b) conditions after throttling=O.l MPa, 1100e(c) water collected in separating calorimeter in 5 minu tes=O.150 liter at 700C(d) water condensed in 5 minutes in throttling calorimeter=3.24kg ..

Q5 Briefly explain the benefits from regenerative feed heating system. Draw theschematic and T-S diagram for a Rankine cycle with regenerative feedheatingand derive condition for optimum regeneration. (12.5)

ORA gas turbine plant working on a Brayton cycle with a regenerator of 70%effectiveness. The air inlet temperature and pressure is 300C and 0.2MPa. Thepressure ratio is 7 and maximum cycl~ temperature 1000oe. Assuming turbineand compressor efficiency as 90% and 80% respectively, find increase inefficiency due to regenerator. (12.5)

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Exam Roll No ,. .cD

END TERM EXAMINATION(Please write your Exam Roll No.)

~ T_H_I_RD__ S_E_M_ES_T_E~.lB.TECH.l DECEMBER-20 12

jPaper Code: ETME207 .. .. Subject: Mechanics of Solids,Time: 3 Hours Maximum Marks :75r---------------·-- -.-...---~------------.-Note: Attempt any five questions including Q.no.l which is compulsory.

Select at least one questi0!l from each unit. Assume missing data, if any.

Ql (al A straight bimetallic strip of copper and steel free at ends is heated. The strip willexpand such that-(i) Both are under tension (ii)Both are under compression(iii)Copper will be under compression and steel under tension.(iv) Copper will be under tension and steel under compression.

(b) Volumetric strain in thin cylindrical shell is-(i) Longitudinal strain + circumferential strain(ii) Longitudinal strain +2 circumferential strain(iii)2xLongitudinai strain + circumferential strain(iv) 2xLongitudinal strain+2 circumferential strain

(cl Area under 'shear force diagram is-(i) Load at that point (ii) S.F. at that point(iii)Bending point at that point (iv)All of these.

(d) The stress in a beam shall be lower if its- .(i) Section modulus is zero (ii) Section modulus is low(iii) Section modulus is high (iv)None of these.

(e) A horizontal beam with square cross-section simply supported with sides of thesquare horizontal and vertical and carries a distributed loading that producesmaximum bending stress er in the beam. When the beam is placed with one of thediagonals horizontal, the maximum bending stress will be-(i) .J2a (ii) er (iii) (11-J2')er (iv)2er.

(f) A rectangular section beam subjected to a bending moment M varying along itslength is required to develop same maximum bending stress at any cross section. Ifthe depth of the section is constant then it will vary as-(i) M (ii).JM (iii)M2 (iv) 11M.

(g) The deflection of a simply supported beam of span '1' under concentrated load 'W' atthe centre is-(i) W13/12EI (ii)WP/24EI (iii)W13/48EI (iv)W13/96EI

(h) The maximum deflection of a simply supported beam of span '1' carrying auniformly distributed load 'w' per unit length-(i) 5w14/484EI (ii) 5w14/584EI (iii)5w14/684El (iv)5w14/384EI

(i) If two shafts are connected in parallel, find which statement is correct(i) Shear stress in each shaft is the same(ii)Torque in each shaft is the same.(ii) Torsional rigidity in each shaft is the same(iii) Angle of twist in each shaft is the same

OJ The outside diameter of a hollow shaft is twice its inside diameter. The rl1tio of itstorque carrying capacity to that of solid shaft of the same outside diameter is-(i) 15/16 (ii) % (iii)Y2 (iv) 1/16 (2.5xlO=25)

UNIT-IQ2 (a) A steel bar is carrying a number of axial loads as shown in fig.I. The diameter of

portions AB, BC, CD is 25mm, 30mm, 40mm respectively. Calculate the (i) Normalstresses in each portion of the bar. (ii) What are the changes in correspondingportions? (E=200x109N/m2) (5.5)

p.T.a.

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[-2-](b) A threaded rod of 25mm diameter is passed through a brass tube of 30mm inte

diameter and 3smm external diameter. The length of tube is 1000mm and closedthin rigid washers and fastened by nuts and screw on the rod as shown in fig.2. Thenut is so tightened till compressive force in the tube is 8kN. Find out the stresses inthe tube and the steel rod. (Es=200GPa, Eb=80GPa) (7)

Q3 (a) Fig.3 shows a composite bar which is rigidly fixed at the end supports. Temperatureis raised by 700C. Find the stresses in A, B, C (i) if supports are rigid (ii) thesupports yield by an amount 0.6mm. (7)(Es=200xl09N/m2 C1.s=12xlO-6per 0C,EA=88xl09N/m2 C1.s=20xlO-6per 0C,Eb=95xl09N/m2 C1.s=15xlO-6per 0c)

(b) Explain any three Theories of Failures. (5.5)

UNIT-IIQ4 (a) A beam with overhang at one end and carrying a uniformly distributed load over the

whole length is shown in figA. Draw the S.F. and B.M. diagram. (61

(h) A beam of I-ci~oss section with a top flange 100mm and 20mm thick, bottom flange150mm and 50mm thick and web 200mm deep and 20mm thick. The beam issimply supported on a span of Sm. Find the safe distributed load on the beam if thetensile stress is not to exceed 25N/m2. Also, calculate maximum compressive stress.(6.5)

Qs (a) A composite beam circular in section is made up of two materials (steel andaluminium) as shown in fig.5. Assuming no slip between the components, determinethe maximum stresses induced in each material, a bending moment of magnitude100kN-m is applied to the section. (Es=3Ea). (6)

Q6

(b) A 4m long cantilever beam of uniform cross section 120mm wide and 300mm deepis loaded with 30kN at the free end. In addition to this, it carries a uniformlydistributed load of 20kN/m run over the entire length; find the maximum. slope andmaximum deflection. (E=210GPa) (6.5)

UNIT-III(a) Explain and derive Euler's Equation. (61(b) A short hollow cast iron column has 400mm external diameter and 100mm internal

dia. A vertical compressive load of 400kN ('J.ctsat an eccentricity of 100mm fromcentre. Determine maximum values of stresses on extreme fibres. (6.5)

Q7 (a) Develop relation between T, 8, G and 1:. (6)(b) An aluminium wire of 6mm diameter is twisted one complete rotation without

exceeding shearing stress of sON/mm2. Take G=28xl09N/m2. Determine the lengthof wire. (6.5)

UNIT-IVQ8 (a) A thin cylindrical shell of thickness 6mm and 400mm in diameter is subjected to an

internal pressure which produces a strain of 0.0005 in diameter. Determine theinternal pressure and consequent hoop stress and longitudinal stress.(E=200xI09N/m2, /1=0.25) (6.51

(b) Explain Lame's Theorem. (6)

Q9 (a) Derive an expression for the deflection and stiffness of close-coiled helical springunder axial loading. (6)

(b) A safety valve blows off at 2N/mm2. Its diameter is 60mm. It is held by close coiledhelical spring. The mean diameter is 150mm and initially it is compressed to ISmm.Determine the wire diameter of the spring and number of turns if maximumallowable shear stress is 60N/mm2. Take G=O.8xl05N/mm2. (6.5)

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END TERM EXAMINATION

cnExam Roll No.....••.......•......• :.(Please write your Exam Roll No.)

THIRDSEMESTER DEC.-JANUARY-2012-13

Paper Code:ETME209 Subject: Production TechnologyTime: 3 Hours Maximum Marks :75

I Note:Attempt all questions. Internal choice is indicated.

QI Answer the following:-(a) Briefly describe aspiration effect and ways to tackle it. (2)(b)Enumerate the functions and explain the role of organic additives

used in green sand casting. (2)(c) Briefly explain the principles underlying design of riser. (2)(d) Define centerline shrinkage and centre-line feeding resistance. (2)(e) What are gas holes and pin holes? Based on what features can you

identify these casting defects? (2)(1)What is role of recrystallization temperature in metal forming?

Describe in brief. (2)(g) Distinguish between working and cold working processes. (2)(h)Briefly describe different types of rolling mills. (2)(i) Briefly describe power source characteristics and arc characteristics

in electric arc wedding. (2)Ul Explain with the help of a block diagram salient feature of a draw die. (2)(k)What is duty cycle of an arc welding power source? What is its

significance? (2)(1) Name and briefly describe a method that you suggest is suitable for

manufacturer of powder of high temperature materials (eg. Tungsten).(3)

Q2 (a) Design a downsprue, avoiding aspiration effect to deliver liquid castiron (density of liquid metal=7800kgjm3) at a rate of IOkgjsec againstno head at the base of the sprue. Neglect frictional and oFifice effects.Take height of liquid column in pouring basin as 6cm and the heightof sprue as 20cm. (4)

(bl Discuss what is dross and methods of its removal. Explain how doesit affect soundness of the casting. (4)

(c) Discuss the defects-scab, blow and scar. Enumerate their causes andpossible remedies. (4.5)

OR(a) A block of steels of size 35x35x60cm3 is required to be cast by top

gate of 3.89cm2 cross-section. Total head above the gate is 24cm.Design the sprue to avoid aspiration effect. Solidification temperatureof steel is 15390C and it is poured at 1800C above it. If the liquidmetal undergoes a thermal shrinkage of 4.5xl06cm3 jC-cm3 and afurther solidification shrinkage of 2%, design top riser. Calculate thetotal filling time (inclusive of gating, mould and riser). Take the lengthof runner as 8cm. (8)

(bl How is the pouring temperature of liquid metal established? Explainstandard spiral mould method for testing of fluidity of liquid metal. (4.5)

Q3 (a) Give percentage composition of green moulding sand. Discuss effect ofgrit, shape and water content on mould strength, permeability andother mould properties. . (4)

(b) Describe what are gagger and chaplets. Briefly discuss criteria basedon which chaplets are designed used in.mO"!..11ds. (4.5)

P.T.O.

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(c) Write short notes on moulding sand, facing sand, parting sand ancore sand. Support your answer with the characteristics of thesesands and their functions / applications. (4)

Q4 (a) How are arc welding electrodes classified? Give at least one examplesof the process that makes use of each type of electrode. (3.5)

(b)What is the role of electrode polarity in arc welding process? Explainits significance. (4)

(c) Name and explain an arc welding process that can be used for weldingof thin sheets.' (5)

OR(a) Explain in detail the Electroslag Welding (~SW) process with a neat

block diagram. Support your answer with its applications, mechanismof heating and progress of welding. (4)

(b)Name and describe each type of flame used in gas welding. Giveapplications of each its types. (3.5)

(c) Discuss the functions of flux used in welding. (2)(d)Describe Metal Inert Gas Welding Process. (3)

Q5 (a) Describe tb-e,Junctions of working rolls and support rolls in a rollingmill. Why is the diameter working rolls kept small? Explain. (2.5)

(b)Explain the im'plications of Roll deflection enumerate its causes andremedies. (2.5)

(c) Describe with a neat sketch different types of stresses that a sheetmetal blank is subjected to during deep drawing process. Outlinedifferent stages in the manufacturing of beverage can. (4)

(d)Which methods of powder manufacture would you suggest for ductilematerials and brittle materials? Explain anyone in brief. (3.5)

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END TERM EXAMINATION .________ T_H_IRD__ S_E_M_ES_T_~R[~_~~H.] DECEMBER~20 12jPaper Code: ETME211 ._ Subject: Mechanics of FluidS]Time: 3 Hours Maximum Marks :75Note: Attempt any five questions including Q.no.l which is compulsory.

Select one question from each unit. Assume missing data if any.

Q1 (a)What is continuum? Under what conditions might the continuumidealization be invalid? (2.5x10=25)

(b)Explain forced vortex flow.(c) Explain the terms: Total acceleration, Convective acceleration and

Local acceleration.(d)Explain the significance of various terms in Bernoulli's equation.(e) Explain the terms: (i) hydraulic grad line (ii) total energy line.(1) Explain 'separation of flows' and discuss the methods used for

controlling separation.~(g) State and explain Prandtl mixing length hypothesis.(h)Define 'apparent stresses' and 'eddy viscosity'.(i) Explain the significance of Reynolds number and Euler number.OJ What is meant by hydraulic similarity between a model and

prototype?

UNIT-IQ2 (a) A painter is painting a wall 3mx4m with a brush 10cm wide and

L25c;m.thick. Th~ thisknes8 of one.c.oatof paint is 0.5mm and theviscosity of the paintis3N-s/m2. Calculate thetotal work required forpaintipg Ol~e..side of th~.wall if he moves the brush with a velocity of10cm/s. (6)

(b)A rectangular plane 1.2m by 1.8m is submerged in water and makesan angle of 30° with the horizontal, the 1.2m side being horizontal.Calculate the magnitude of the net force on one face and the positionof centre of pressure when the top edge of the plane is (i) at the watersurface and (ii)30m below the water surface. (6.5)

Q3 (a) A cylindrical concrete mould 50cm in diameter and 50cm in height isattached to a wooden cylindrical pole of 50cm diameter so that itfloats vertically in water as a marker buoy. Determine the maximumandtninimutn length' of the pole, such that it floats vertically abovefuesurface of the water. Take sp. Gravity of concrete and wood as 3.0and 0.5 respectively. (6.5)

(b)A nozzle is a channel of varying cross-sectional area. Its cross-j sectional 'area converges linearly along its length ..., The. insidediameters at inlet and outlet are 75cm and 25cm respectively and theaxial length is 300mm. Determine the convective acceleration at asection halfway along the axis of the nozzle if the discharge is

3

constant as O.015~. (6)s

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UNIT-IIQ4 (a)A 600 bend in a horizontal plane has its cross-sectional areas at inlet

and outlet equal to 1m2 and 0.5m2 respectively. Calculate themagnitude and direction of the force required to hold the bend inposition if the velocity of water at. inlet is 10m/s a,nd the pressure atinlet and outlet is 40KN/m2 and 30KN/m2 respectively. (6.5)

(b)Water at the rate of 40 litis is flowing through a 150mm diameter firehose at the end of which a 50mm diameter nozzle is flXed. Calculatethe force exerted by the nozzle if the pressure at the inlet of the nozzleis 200kPa. (6)

Q5 (a)The velocity distribution in laminar flow through a pipe is given by

u ~U{I-(:')'} Calculate the average velocity and the kinetic energy

correction factor. (6.5)(b)What is Euler's equation of motion? Derive the equation along a

streamline and obtain Bernoulli's equation from it. (6)..UNIT-III ~

Q6 (a) Briefly describe the Reynolds experiment and mention its significance.(6)(b)A thin film of lubricating oil (J.l = O.9p',_s' 8 = 1260kg / m3) is flowing

uniformly down an inclIned plane 6=30°. Calculate the free surfacevelocity and the flow rate per unit width of the plate, if the depth is5mm. (6.5)

Q7 (a) Assume a linear distributi(mof velocity in the laminar boundary Jayerover a flat plate (u=aO+alY).Obtain the ~alue of 6, 6*and 6. (6.5)

(b)A liquid flows steadily through a long horizontal pipe. Find anexpression for the drop in pressure per unit length of the pipe. (6)

UNIT-IVQ8 (a)The universal velocity distribution for the turbulent flow in a smooth

pipe is given by the equation ~ = 5.5 + 2.51oge yu •. Calculate the ratio ofu. v

the mean velocity to maximum velocity and the radius at which thelocal velocity is equal to the mean velocity. (6.5)

(b) In a city water supply system, water is flowing through a pipe line30cm in diameter. The pipe diameter is suddenly reduced to 20cm.Estimate the discharge through the pipe if the difference in pressureacross the sudden contraction is 5KPa. (6)

Q9 (a) Derive Hagen-Poiseulle equatiQnand explain its significance. (6.5)(b)Explain Flow nozzle and rectangular weir. (6)

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(Please write your Exam Roll No.) Exam Roll No .

END TERM EXAMINATIONTHIRD SEMESTER DECEMBER-2012

Paper Code:ETME213 Subject-;--E-Z-e-c-t-n-'c-a-Z-M-a-c-h-i-n-e-s~1Time: 3 Hours Maximum Marks :75Note:Attempt any five question~-in-c-Z-u--d-ingQ.no.l which is compulsory. I

Assume missing data, if any. !

Q 1 (a)What are the causes of delayed commutation in dc machines? (2)(b)If the brushes in dc machine are moved in the direction of rotation of

the original machine. What will happen to the generator operation? (2)(c) Explain the function of no-volt release in a three point starter. (2)(d)What is load magnetization curve of a synchronous machine? J2)(e)What is the necessity of computing the voltage regulation of

alternators? (2)(f) What are three factors that causes a change of the altmator terminal

voltge as it is loaded? (2)-(g)What are tbe causes of an induction motor operating always at. lagging power factors? (2)(h)Why the slots on the rotor of induction motor are u~ually skewed? (2)(i) For 3$ Induction motor prove that rotor frequency, f2=sf1, where

S=slip and f1=SUpplyfrequency. (3)Ul Why are ac series motors built with large number of armature

conductors? _(2)(k)W1)ysingle phase induction motors are not self starting? . (2)(1)Why an induction motor cannot develop torque when running at

synchronous speed? (2)

Q2 (a) Explain voltage build up process in dc shunt generator. It is foundthat the voltage of dc shunt generator does not build up. Explainvarious possible causes of failure. (6.5)

(b)A 10KW, 6 pole dc generator developes an emf of 200V at 1500rpm.The armature has lap connected winding. The average flux densityover a pole-pitch is 0.9Tesla. The length and diameter of armature are0.25m and 0.2m respectively. Calculate- (6)(i) The flux per pole.(ii)The total number of active conductors in the armature.(iii)torque developed by the machine when armature supplies acurrent of 56A.

Q3 (a)With the help of neat diagram describe the working of a three pointstarter for dc shunt motor. (6)

(b)A 220V shunt motor has armature circuit resistance of 0.20 and fieldresistance of lIon. At no load motor takes 5A and rms at 1500rpm. Ifmotor draws 52A at rated voltage and rated load, calcul.ate the motorspeed and its rated shaft torque in Nm. The rotational losses at noload and full load are the same. Neglect armature reaction. (6.5)

Q4 (a) Sketch the typical torque-speed characteristics of an induction motor.How is this characteristics modified- (6)(i) if rotor resistance is increased.(ii)if rotor reactance is increased. p.T.a.

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(b)A 3-phase, 400V, 50Hz induction motor takes a power inputat its full load speed of 890rpm. The total stator losses are 1the friction and windage losses are 1.5KW. Calculate-(i) Slip(ii)Rotor ohmic losses(iii)Shaft torque(iv)Internal torque

Q5 (a) Calculate the relative values of starting current and star~ing torquesof 9.3 phase squirrel cag induction motor when it is started by- (6)(i) Direct on line starter(ii)Star-delta starter(iii)Auto transformer starter with 60% tapping.

(b)A 3 phase induction motor has a starting torque of 150% andmaximum torque of 250% of full load torque. Neglect stator resistanceand assume constant rotor resistance. Compute-(i) slip at maximum torque(ii) fun load slip (6.5)..

Q6 (a) Explain the mmf method of determining the voltage regulation of analternator. (6)

(b) Derive an expression for power developed in a cylindrical rotorsynchronous motor in terms of. load angle and synchronousimpedance. 'J (6.5)

Q7 (a) Give the constructional features, principle of operation, working ofsingle phase hysteresis ,motor. (6)

. (b) Classify single phase induction motors in accordance with themethods of starting. Discuss capacitor split phase type motor withcircuit diagram, phasor diagram and torque-speed characteristics. (6.5)

Q8 Write short notes on any two of the following:-(a) Speed control of three phase ,induction motor.(b)AC series motor(c) Double revolving field theory

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(6+6.5)

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