BHEL
Placement Paper
Examination 2008
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
#. PERT is: = event oriented technique
#. Bar charts are suitable for: = minor works.
#. ? on a PERT/CPM chart represents: = a significant event representing some mile-stone
#. Electron volt is the unit of : = Energy.
#. Seamless tubes are made by?
#. Reheating in gas turbine results in: = increase of work ratio and decrease of thermal efficiency.
#. Why DC current is not used in transformer?
#. What is the purpose of draft tube in hydraulic turbines: = to convert the kinetic energy into pressure energy.
#. A mass of 100kg is falling from a height of 1m and penetrates the sand to 1m. what is the resistance force of the sand?
#. What kind of abrasive cut off wheel should be used to cut concrete, stone and masonry? =Diamond grit.
#. In break-even analysis, total cost consists of: = Fixed cost + Variable cost.
#. The amount deducted from the salary of workers towards employees provident fund is : =deposited in the account of worker with Provident Fund Commissioner.
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