Last years Papers of BHEL exam

Will you please give me question paper for placement examination of Bharat Heavy Electrical Limited soon ??

Here I am giving you question paper for placement examination of Bharat Heavy Electrical Limited ..

Consider the following expressions indicating the step or impulse response of an initially relaxed control system-
1. (5 – 4e-2+) u(t)
2. (e-2t +5) (u(t))
3 .V(t) + 8e-2t u(t)
4 . V(t) + 4e-2t 4(t)


Those which correspond to the step and impulse response of the same system include-
1&3

Which is the following relate to rational transfer function of a system-
1. Ratio of Fourier transform of output to input with zero initial conditions.
2. Ratio of Laplace transform of output to input with zero initial conditions.
3. Laplace transform of system impulse response.


4. Laplace transform of system unit step response select the correct answer using the codes given below.
Codes
a.) 1 and 4
b.) 2 and 3
c.) 1 and 3
d.) 2 and 4
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


In the case of a 70 MHz 1F carries for a transponder band width of 36 MHz; energy must lie between – MHz.
a.) 34 and 106
b.) 52. And 88
c.) 106 and 142
d.) 34 and 142


Radar used to eliminate clutter in navigational application is –
a.) Pulse radar
b.) Tracking radar
c.) MTI radar
d.) Mono pulse radar


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


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.


In a terrestrial microwave system transmission of signals is achieved through-
a.) reflection from the ionosphere
b.) line of sight mode
c) reflection from the ground
d.) diffraction from the stratosphere.

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.

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.


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 short – 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
As compared to analog multimeters, digital multimeters are –
a.) less accurate
b.) more accurate
c.) equally accurate
d.) none.


When a signal of 10 mV at 75 MHz is to be measured then which of the following instruments can be used –
a.) VTVM
b.) Cathode ray oscilloscope
c.) Moving iron voltmeter
d.) Digital multimeter

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


The coupling that produces minimum interference with frequency response is-
a.) Direct coupling
b.)Impedance coupling
c.) R C coupling
d.)Transformer coupling


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 a critical value

When an inductor tunes at 200 KHz with 624 pF capacitor and at 600 KHz with 60.4 pF capacitor then the self capacitance of the inductor would be –
a) 8.05 pF
b) 10.05pF
c.) 16.01pF
d.) 20.01pF


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


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


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)


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


RF amplifier of an A.M. receiver is normally biased in –
a.) Class 'A'
b.) Class 'b'
c.) Class 'C'
d.) None


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

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 the
resistance 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 gravity
of the liquid.

5)Two cars travell in same direction at 40 km/hr at a regular distance. A car comes in a opposite
direction in 60km/hr. It meets each car in a gap of 8 seconds. What is the distance between them?
6)A simple problem involing in hoops stress. For sphere: M= [3/2]*p*V*[density of pressure vessel
material/Maximum working stress it can tolerate] For Thin walled pressure walls: Hoops stress or
stress 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 manifactured in which process. (cupola process)
11)What percentage of carbon is preset in pig iron. (4.5 to 6%)

12)Water is available at 10m height. What is the pressure available? (pressure=density*g*height;
p=1000*9.81*10; p=98100N/m2)

13)What will happen if the speed of the centrifugal pump doubles.
14)The unit eV is widely used in ? (Nuclear and atomic physics)
15)What will happen to the resistance, when the diameter of the conductor is doubled?

16)The power comsumed by a electrical device is 1000W at 250V, What is the resistance in the device?
(Power= Voltage*current; Current=Power/Voltage, Current,I=1000/250=4
amps. V=IR, Therefore R=250/4=62.5 ohms)
17)Why DC current is not used in transformer.
18)On what principle the sonar/ radar( I dont remember) works?
19)Bending moment diagram for the UDL is in what shape?
20)Function of the distributor in petrol vehicles? (Spark timing)
21)Which is not present in CI engines? (carburrettor)

22)What will happen if one cylinder recieves more amount of fuel spray from injectors than other
injectors?

23)Purpose of draft tube in hydraulic turbines? (The purpose of a draft tube is toconvert some of the
kinetic energy of the flow from the runner (the rotating part of the turbine) intopressure energy and
thereby increase the efficiency ofthe hydro power turbine. )

24)What is the effect or reheater in the gas turbine? (The advantage of reheater is significantly
increased thrust; the disadvantage is it has very high fuel consumption and inefficiency)

25)Problems in involving with fricition coefficient.
26)Factor of safety = Yeild stress/Working stress.
27)Which is the example of non parallel power transmission (Universal coupling)
28)For perpendicular shafts worm gear is used.

29)A planet gear with 25 teeth is meshed with a sun gear of 100 teeth. Both are connected using a arm.
How many rotations are needed for planet gear to complete one rotation around the sun gear?
30)What is equivalent spring constant for spring in parallel?
31) Some questions was asked related to boundry layer and vortex flow.
32) 5 questions were asked in PERT, Process planning, Product planning, Break even analysis.
33)How are tungsten and sintered composite materials are machined? (Electro Discharge Machining,
EDM)

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Answered By StudyChaCha Member