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BHEL Written Test Technical Questions and answers
1. What percentage of carbon is preset in pig iron. (4.5 to 6%)
2. Water is available at 10m height. What is the pressure available? (pressure=density*g*height;p=1000*9.81*10; p=98100N/m2)
3. What will happen if the speed of the centrifugal pump doubles.
4 . The unit eV is widely used in ? (Nuclear and atomic physics)
5. What will happen to the resistance, when the diameter of the conductor is doubled?
6. The power consumed by a electrical device is 1000W at 250V, What is the resistance in thedevice?(Power= Voltage*current; Current=Power/Voltage, Current, I=1000/250=4amps. V=IR, Therefore R=250/4=62.5 ohms)
7. Why DC current is not used in transformer.
8. On what principle the sonar/ radar works?
9. Bending moment diagram for the UDL is in what shape?
10.Function of the distributor in petrol vehicles? (Spark timing)
11.Which is not present in CI engines? (carburetors)
12.What will happen if one cylinder receives more amount of fuel spray from injectors than other injectors?
13.Purpose of draft tube in hydraulic turbines? (The purpose of a draft tube is to convert some of the kinetic energy of the flow from the runner (the rotating part of the turbine) into pressure energyand thereby increase the 
efficiency ofthe hydro power turbine.)
14.What is the effect or reheated in the gas turbine? (The advantage of reheater is significantly increased thrust; the disadvantage is it has very high fuel consumption and inefficiency)
15.Problems involving with frication coefficient.
16.Factor of safety = Yeild stress/Working stress.
17.Which is the example of non parallel power transmission (Universal coupling)
18.For perpendicular shafts worm gear is used.
19.A planet gear with 25 teeth is meshed with a sun gear of 100 teeth. Both are connected using aarm. How many rotations are needed for planet gear to complete one rotation around the sun gear?
20.What is equivalent spring constant for spring in parallel?
21.How are tungsten and sintered composite materials are machined? (Electro Discharge Machining, EDM)
22.An elevator weighing 1000kg attains an upward velocity of 4m/sec in two seconds with uniform acceleration. The tension in the supporting cables will be = 1200kg.
23. A 13m ladder is placed against a smooth vertical wall with its lower end 5m from the wall. What should be the co-efficient of friction between ladder and floor so that it remains in equilibrium. =0.21
24. A car is moving with a velocity of 60km/hr and possesses energy of 5×105 joules. The mass of the car will be. =3000kg.
25.If l is the span of a light suspension bridge whose each cable carries total weight (w) and the central diop is y, the horizontal pull at each support is: = wl/y OR
26. A beam of length l, having uniform load w kg/unit length is supported freely at the ends. The moments at mid span will be: = wl2/8.
27. A boiler shell 200cm dia and plate thickness 1.5cm is subjected to internal pressure of 1.5MN/m2, then the hoop stress will be. = 100N/m2
28.100KW is to be transmitted by each of two separate shafts. A is turning at 250rpm and B at300rpm. Which shaft must have greater diameter.: = B
29.Two identical leaf springs of spring constant k are arranged like cantilevers in parallel and attached at free end by a spring of spring constant k. The equivalent spring constant of combinationis; = 1.5k.
30.Automobile steering gear is an example of: = lower pair.
31.The type of coupling used to join two shafts whose axes are neither in same straight line nor parallel, but intersect is. = Universal coupling.
32.The ratio of two specific heats of air is equal to. = 1.41
33.A perfect gas at 270C is heated at constant pressure till its volume is double. The final temperature is = 3270C
34. An engine operates between temperature of 9000K and T2 and another engine between T2 and8000K. For both to do equal work, value of T2 will be. = 6500K
35.Internal energy of a substance depends on = Temperature
36.Work done in compressing 1kg of gas adiabatically from p1,V1,T1 to p2, V2, T2 is equal to =Cv(T2-T1)
37. The unit of entropy is = J/kg 0K
38.Indicated power of a 4-stroke engine is equal to = pLAN/2
39.Which of the following is not an internal combustion engine :
a) 2 stroke petrol engine
b)4 stroke petrol engine
c) Diesel engine
d) steam engine
e) Gas turbine.
Ans : (d)
40.If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the:
a) exhaust will be smoky
b) piston rings would stick into piston grooves
c) exhaust temperature will behigh
d) engine starts overheating
e) all of the above.
Ans : e
41.In most microwave communication link rain drop attenuation is caused due to-
a) scattering of microwaves by water drops of specific size.
b) scattering of microwaves by a collection of droplets acing as a single body.
c) absorption of microwaves by water and consequent heating of the liquid
d) absorption of the microwaves by water vapor in the atmosphere.
42.When a (75 - j40)W load is connected to a coaxial line of Z0 = 75 W at 6MHz then the load matching on the line can be accomplished by connecting-
a) A shor – circuited stub at the load
b) An inductance at the load.
c) A short circuited stub at a specific distance from the load
d) none of the above
43.As compared to analog multimeters, digital Multimeters's are –
a) less accurate
b) more accurate
c) equally accurate
d) none.
44.When a signal of 10 mV at 75 MHz is to be measured then which of the following instrumentscan be used –
b) Cathode ray oscilloscope
c) Moving iron voltmeter
d) Digital multimeter
45. Amplifier of class B has high theoretical efficiency of 78.5 percent because-a) It is biased almost to saturation
b)Its quiescent current is low
c)It’s output is an exact replica of it’s input
d)It is biased well below cut off
46. The coupling that produces minimum interference with frequency response is-
a) Direct coupling
b) Impedance coupling
c) R C coupling
d)Transformer coupling
47. A superconductor is a –
a) A material showing perfect conductivity and Meissner effect below a critical temperature
b) A conductor having zero resistance
c) A perfect conductor with highest di-magnetic susceptibility
d) A perfect conductor which becomes resistance when the current density through it exceeds acritical value
48. When an inductor tunes at 200 KHz with 624 pF capacitor and at 600 KHz with 60.4 pF capacitorthen the self capacitance of the inductor would be –
a) 8.05 pF
b) 10.05pF
c) 16.01pF
d) 20.01pF
49. The Q of a radio coil -
a) is independent of frequency
b) increases monotonically as frequency increases
c) decreases monotonically as frequency increases
d) increases upto a certain frequency and then decreases beyond that frequency
50. A pressure of 25m of head of water is equal to. =245kN/m2
BHEL Placement Paper February 2011 :-
1. Unit of Entropy (J/kg K or kJ/kg K)
2. A mass of 100kg is falling from a height of 1 m and penetrates the sand into for 1 m. What is theresistance force given by sand.
3. Ratio of specific heats of air. (1.41)
4. A body weighs 3 kg in air. If it is submerged in a liquid, it weighs 2.5 kg. What is the specific gravityof the liquid.
5. Two cars travel in same direction at 40 km/hr at a regular distance. A car comes in a oppositedirection in 60km/hr. It meets each car in a gap of 8 seconds. What is the distance between them?
6. A simple problem involving in hoops stress. For sphere: M= [3/2]*p*V*[density of pressure vesselmaterial/Maximum working stress it can tolerate] For Thin walled pressure walls: Hoops stress orstress in the radial direction =p*r/2t
7. A problem in force calculation in a body moving in a inclined surface.
8. Composition of bronze. (Copper+zinc)
9. Compostion of stainless steel.(iron+chromium+nickel+carbon)
10.CI is manufactured in which process. (cupola process)
11.Consider the following expressions indicating the step or impulse response of an initially relaxedcontrol system-
a) (5 – 4e-2+) u(t)
b) (e-2t +5) (u(t))
c) V(t) + 8e-2t u(t)d)
V(t) + 4e-2t 4(t)
12. Which is the following relate to rational transfer function of a system-
a) Ratio of Fourier transform of output to input with zero initial conditions.
b) Ratio of Laplace transform of output to input with zero initial conditions.
c) Laplace transform of system impulse response.
13. Laplace transform of system unit step response select the correct answer using the codes givenbelow. Codes
a) 1 and 4
b) 2 and 3
c) 1 and 3
d) 2 and 4
14. For the signal g (t) – 10 cos (50 pt) cos2 (150at) The Nyquist sampling state in t seconds is
a) 150 samples per second
b) 200 samples per second
c) 300 samples per second
d) 350 samples per second
15. In the case of a 70 MHz 1F carries for a transponder band width of 36 MHz; energy must liebetween – MHz.
a) 34 and 106
b) 52. And 88
c) 106 and 142
d) 34 and 142
16. Radar used to eliminate clutter in navigational application is –
a) Pulse radar
b) Tracking radar
c) MTI radar
d) Mono pulse radar
17. The 1.55 mm windows is not yet in use with fiber optic systems because –
a) The attenuation is higher than at 0.85 mm
b) The attenuation is higher than at 1.3mm
c) Suitable laser devices have not yet been developed
d) It does not lend itself to wavelength multiplexing
18.Pre-emphasis in FM systems involves-
a) Compression of the modulating signal
b) Expansion of the modulating signal
c) Amplification of lower frequency components of the modulating signal.
d) Amplification of higher frequency components of the modulating signal.
19.In a terrestrial microwave system transmission of signals is achieved through-a.) reflection from the ionosphere
b.) line of sight modec) reflection from the ground
d.) diffraction from the stratosphere.
20. Casse grain feed is used with a parabolic reflector to
a) increase the gain of the system
b) increase the bandwidth of the system
c) reduce the size of the main reflector
d) allow the feed to be placed at a convenient point.
21. What kind of abrasive cut off wheel should be used to cut concrete, stone and masonry?=Diamond grit.
22. In break-even analysis, total cost consists of: = Fixed cost + Variable cost.
23.The amount deducted from the salary of workers towards employees provident fund is :=deposited in the account of worker with Provident Fund Commissioner.
24. PERT is: = event oriented technique
25. Bar charts are suitable for: = minor works.
26.? on a PERT/CPM chart represents: = a significant event representing some mile-stone
27. Electron volt is the unit of : = Energy.
28. Seamless tubes are made by?
29. Reheating in gas turbine results in: = increase of work ratio and decrease of thermal efficiency.
30. Why DC current is not used in transformer?
31. When a generator of internal impedance and operating at 1GHz feeds a load via a coaxial line of characteristic impedance 50 ohm then the voltage wave ratio on the feed line is –
a) 0.5
b) 1.5
c) 2.5
d) 1.75
32. The coding system typically used in digital telemetry is –
a) PPM (pulse position modulation)
b) PAM (pulse amplitude modulation)
c) PCM (pulse code modulation)
d) PDM (pulse duration modulation)
33.Radiation pyrometers are used for the measurement of temperature in the range of –
a) -2000C to 5000C
b) 00C to 5000C
c) 5000C to 12000C
d) 12000C to 25000C
34.RF amplifier of an A.M. receiver is normally biased in –
a) Class 'A'
b) Class 'b'
c) Class 'C'
d) None
35 .The value of gate voltage for the operation of enhancement of only N channel MOSFET has to be –
a) High positive
b) High negative
c) Low positive
d) Zero
36. The spark plug gap is normally maintained at: = 0.45 to 0.6mm
37. A distributor in spark ignition engines performs the function of : = Providing the correct firingorder in engine
38. Which of the following does not relate to C.I. engine::
a) fuel pump
b) fuel injector
c) governor
e) flywheel
Ans : d
39. Air fuel ratio in a jet engine is = 60:1
40. What is the value of Prandtl No.?

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