| Re: Question Papers of BHEL and SAIL Exams of Electronics
BHEL is the Bharat Heavy Electrical Limited.
It conducts exams for various branch of engineering.
SAIL is Steel Authority of India Limited.It is one of the largest steel making companies of India. It recruits students from various fields. There is a written test and a personal interview.
As you want the previous year Question Papers of BHEL and SAIL Exams of Electronics stream so here I am providing you
When a inductive coil connected to a 200 V, 50Hz ac supply with 10A current flowing through it
dissipates 1000 watts then which of the following will have least value in ohms
a.) Resistanceb.) Reactancec.) Impedance d.) None
Oscillator crystal are made of –
a.) Silicon
b.) Germanium
c.) Quartz
d.) None
For small size, high frequency coils, the most common core material is‐a. )Airb. )Ferrite c.) Powdered ion
d.) Steel
If we have a parallel plate capacitor of plate area ‘A’ and plate separatoin t and having a capacity C and a
metallic plate r of area A and of negligible thickness is introduced in the capacitor at a distance from
either of the two plates as shown in the given figure then the capacity of the capacitor will become –
a.)
b.) C
c.) 2C
d.) 4C
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
Sparking occur when a load is switched off because the circuit has high –
a.) Inductance
b.) Capacitance
c.) Resistance
d.) None
Sparking between contacts can be reduced by inserting a –
a.) Resistance in the line
b.) Capacitor in series with contacts
c.) Capacitor in parallel with contacts
d.) None
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
The input gate current of a FET is –
a.) a few microamperes
b.) negligibly small
c.) a few milliamperes
d.) a few amperes
In the following fig. with R = 30k, the value of current through 2 K resistor is –
a.) 25 mA
b.) 40 mA
c.) 25/16 mA
d.) 10 mA
A step recovery diode –
a.) has on extremely short recovery time
b.) conducts equally well in both directions
c.) is mainly used as a harmonic generator
d.) is an ideal rectifiers of high frequency signals
In order to get maximum undistorted output signal from CE amplifier with VCC 10V, the value of VCE (Q)
should be approximately‐ a.) 0.1V
b.) 5V
c.) 10V
d) V
In a FET the electrode, which corresponds to collector in bipolar transistor, is –
a.) source
b.) drain
c.) gate
d.) none
The device which acts like an NPN and a PNP transistor connected base to base and emitter to collector
is –a.) Triacb.) UJT c.) Diac
d.) SCR
A typical optical fibre has –
a.) High refractive index core and low refractive index cladding
b.) Low refractive index core and high refractive index cladding
c.) Both a and b
d.) None
In the following figure circuit diagram of an op‐amp based is shown. The ratio is equal to –
a.) 9
b.) 11
c.) 10
d.) 21
When a loud speaker is connected across the terminals A and B of the network shown in the fig. then its
impedance to obtain maximum power dissipation in it will be – a.) 3 – j1 b.) 3 + j9
c.) 7.5 + j 2.5
d.) 7.5 – j 2.5
In the lattice network, the value of R for the maximum power transfer to the load – a.) 5 b.) 6.5
c.) 8
d.) 9
For a lossy transmission line short circuited at the receiving end, the input impedance is given by (Z0 is
the characteristic impedance, Ö is the propagation constant and l is the length of the line‐a.) Z0 cot h
Ölb.) Z0 cot Öl c.) Z0 tan h.Ö l
d.) Z0 tan Öl
The approximate thickness of the radome wall should be –a.) lb.) l/4 c.) l/2
d.) l/8
A relatively permanent information is stored in
a. ) ROM
b.) RAM
c.) PROM
d.) Volatile memory
The rise time of the RC network shown in the given figure is approximately equal to – b.) RC
c.) 2RC
d.) 4RC
If in the network shown in the fig. initially a steady state is attained by closing the switch ‘s’ and then if
the switch is opened at t = 0, then the current i(t) through the inductor will be – a.) cos50tA b.) 2A
c.) 2cos100tA
d.) 2sin50tA
When the p network of figure – I and T‐network of figure – II are equivalent then the values of R1, R2
and R3 will be respectively – a) 9W, 6W and 6W b.) 6W, 6W and 9W
c.) 9W, 6W and 9W
d.) 6W, 9W and 6W
When the impedance matrices of a two port networks are given by and , then if these two networks are
connected in series then the impedance matrix of the resulting two‐port network will be –
d.) indeterminate
Joule/coulomb is the unit of ‐ a.) Electric field potential b.) Potential c .) Charge
d.) None of the above
The electric field line and equipotential lines‐ a.) Are parallel to each other
b.)Are one and same
c.) Cut each other orthogonally
d.)Can be inclined to each other at any angle
For a lossy transmission line short circuited at the receiving end, the input impedance is given by (When
Z0 is the characteristic impendence g is the propagation constant and L is the length of the line
When two equal positive point charges are placed along X‐ axis at X1 and –X1 respectively then the
electric field vector at a point P on the positive Y‐axis will be directed‐ a.) In the +x direction
b.) In the –x direction
c. ) In the +y direction
d.) In the –y direction
The directions of and in TEM mode transmission line with respect to the direction of propagation are‐ a.) Both and are transverse to the direction of propagation
b.) is and are transverse and h has a component in the direction of propagation
c.) is entirely transverse and has a component in the direction of propagation
d. ) is entirely transverse and has a component in the direction of propagation
The lowest TM mode in a rectangular waveguide of cross –section a x b with a>b will be‐ a.) TM01
b.)TE10
c.) TM112
d.)TE11
When a transmitter in a free space radiates a mean power of ‘p’ watts uniformly in all directions then at
a distance d sufficiently far from the source in plane the electric field E should be related to p and d as –
. When a dipole antenna was radiating with some excitation in free space radiating a certain amount of
the power v if then this antenna is immersed in a lake where water is non‐dissipative but has a dielectric
constant of 81, then the radiated power with the same excitation will be
a.) Decrease to finite non‐zero value
b.)Remain the same
c. )Increase
d.)Decrease to zero
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 accurateb.) 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.) VTVMb.) Cathode ray oscilloscope c.) Moving iron voltmeter
d.) Digital multimeter
Which of the following statement is true about two wattmeter method for power measurement in three
phase current ?a.) power can be measured using two wattmeter method only for star connected three
phase circuits.b.) when two meter show indentical readings, in the power factor is 0.5. c.) when power
factor is unit, one of the wattmeter reads zero
d.) when the reading of the two wattmeters are equal but of opposite sign, then the power factor is zero
–
When a capacitance transducer has two plates of area 5cm2 each, separated by an air gap of 2mm than
the displacement sensitivity in pf/cm due to gap change would be –a.) 11.1b.) 44.2 c.) 52.3
d.) 66.3
The Q of a radio coil –a.) is independent of frequencyb.) 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.) 0.5b.) 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
In the given figure band structure is shown. It is of –
a.) Gallium Avesenide (GaAs)
b.) Silicon (Si)
c.) Copper (Cu)
d.) Germanium (Ge)
When anode is positive with respect to cathode in an SCR, the numbers of blocked p‐n junction is –
a.) 1
b.) 2
c.) 3
d.) 4
The circuit symbol for a GTO is
a. b.
c. d.
In the given fig. mark out the type of Cyclo converters
a.) 1 phase to 1 phase with continuous conduction
b.) 1 phase to 1 phase with discontinuous conduction
c.) step up device
d.) 3 phase to 1 phase device
In the given fig. A‐1, C=5, m H and C=20 m F, C is initially charged to 200 V. After the switch.
S is closed at t = 0 the
maximum value of current and the
time at which it reaches this value are respectively.
a.) 400 A, 15.707 mS
b.) 50 A, 30 mSc.) 100 A, 62.828 mSd.) 400 A, 31.414 mS
SAIL MT Electronics Model Question Paper
Q. Power diode is generally made from
a) Silicon
b) Germanium
c) Both
d) None of these
Q. When the both junction of NPN diode is reverse biased, then the diode is in which mode
a) Active
b) Cutoff
c) Saturation
d) inverted
Q. Which transistor mode gives the inverted output
a) Common Emitter
b) Common Base
c) Common Collector
d) None of these
Q. Which coupling gives the higher gain in case of amplifier
a) Capacitor coupling
b) Impedance coupling
c) Transformercoupling
Q. Which distortion is least objectionable in audio amplification
a) Phase
b) Frequency
c) Harmonic
d) Intermediation
Q. A narrow band amplifier has a band pass nearly…………of central frequency
a) 33.3%
b) 10%
c) 50%
Q. Phase shift oscillator consists
a) RL
b) RC
c) RLC
Q. Multivibrater Produces
a) Sine wave
b) Square wave
c) Smooth wave
d) sawtooth
Q. Convert the 101101 Binary number into octal no
a) 65
b) 55
c) 51
d) 45
Ans: 55
Q. 10 in BCD
a) 10100
b) 1100
c) 010111
d) None of these
Ans: None of these
Q. Which PNP device has a terminal for synchronizing purpose
a) SCS
b) Triac
c) Diac
d) SUS
Q. Addition of indium in semiconductor crystal makes
a) PNP
b) NPN
Q. Free electron exists in which band
a) 1
b) 2
c) 3
d) Conduction band
Q. Ripple factor of half wave rectifier
a) 1.21
b) 0.48
c) 0.5
Q. Transistor that can be used in enhancement mode
a) NPN
b) UJT
c) JFET
d) MOSFET
Q. Following contributes to harmonic distortion in Amplifier
a) +Ve feedback
b) –Ve feedback
c) Defective active device
Q. High cutoff frequency
a) CB
b) CC
c) CE
Q. Which is used as data selector?
a) Encoder
b) Decoder
c) modulator
d) Demodulator
Q. Read write capable memory
a) RAM
b) ROM
c) Both
d) None of these
Q.the radix or base of hexadecimal number system is -----------
a) 8
b) 16
c) 5
d) none of these
Ans: 16
Q.the no of 1’s in the binary representation of the expression 162*9+162*7+16*5+3 are
a) 10
b) 23
c) 6
d) 4
Q. the no of latches in F/F are -------
a) 1
b) 2
c) 3
d) 4
Q.how many flip-flops are required to construct Mod -12 counter
a) 5
b) 4
c) 12
d) none
Ans: 4
Q. which logic gate has the output is compliment of its input ----------
a) OR
b) AND
c) NOT
d) X-OR
Ans: NOT
Q.no.of 2-input multiplexers needed to construct a 210 input multiplexer…….
a) 12
b) 31
c) 20
d) 16
Q.By adding inverters to the inputs and output of a AND gate we can obtain ……………
a) OR
b) AND
c) NOT
d) X-OR
Ans: X-OR
Q.how many NAND gates are needed to realize OR gate --------------
a) 1
b) 2
c) 3
d) 4
Ans: 3
Q.which is the first integrated logic family ---------------
a) RTL
b) DTL
c) TTL
d) none of these
Q. Which logic gate has output high if and only if all inputs are low ---------?
a) NOR
b) NAND
c) X-NOR
d) AND
Ans: NAND
Q.According to Boolean algebra 1+A+B+C =
a) A
b) A+B+C
c) 1
d) none of these
Ans: 1
Q. If a=0x6db7 and b=0x2ae9 then what is the value of a”b--------------
a) binary number for 1001.1101?
b) decimal number for 19?
c) excess-3 code for 29?
Q.what is the value of A'+1 ?
a) A
b) A'
c) 1
d) none of these
Ans: 1
Q.2 in 4 bit number one bit indicates sign of the number then the locations are from
a) -8 to 8
b) -7 to 7
c) -16 to 16
d) None
Q.Avalanche photo diode is used when compared to PIN diode bcz
a)larger band width
b)high sensitivity
C)-------
d)--------
Q.some non zero DC voltage is to RC low pass circuit then the DC voltage in the output contains
a) Same as in input
b) Higher than input
c) Zero
d) Slightly increases
Q.if the output of the gate is always high then the gates applied to this logic are 0,0
a) NAND and EX-NOR
b) NAND and NOR
c) AND and X-NOR
d) OR and XOR
Ans:a
Q.Thermal Run away is not possible in FET bcz the flow of
a)minority careers
b)Transconductance
c)_____
d)none
Ans : minority careers
Q.which of the following is/are true about 1's and 2's compements:
i)In 1's complement form. 0 has two representations
ii)in 1's complement, the magnitude of lowest number is equal to the magnitude of highest number
iii)In 2's complement, 0 has two representations
a) i only
b) i and ii
c) iii only
d) all of these
Q.In the hybrid parameter model of a transistor reverse transfer voltage ratio and forward transfer
current ratio are respectively given by:
a) h11 and h21
b) h12 and h11
c) h21 and h11
d) None of these
Q.The largest negative no can be represented with 8 bits in 2's compliment representation?
a)-256
b)-255
c)-127
d)-128
Ans: -128
Q. How many NAND gates required to implement AB+CD+EF
a) 1
b) 2
c) 3
d) 4
Ans: 4
Q. Transparent latch is seen in which type of flip flop
a) SR FF
b) D FF
c) JK FF
d) D FF
Ans: D FF
Q. Odd parity generator uses which logic?
a) Digital
b) Analog
c) Sequential
d) none
Q. Which type of ADC is fastest?
a) SARC
b) Counter type
c) Intigrated type
d) Flash
ANS: Flash/Parallel
Q. Which one of the following is fastest read/writable memory?
a) PROM
b) EEPROM
c) Flash
d) none
Ans: Flash
8. In array programming which one is used
a) SISD
b) PISD
c) MISD
d) None
Q.Which one of the following has high I/p impedance
a) CC
b) CB
c) CE
d) None
Q. The maximum time allowed time for each flip flop for a mod 10 synchronous counter if each flip flop
delay is 25ns.
a) 25 ns
b) 50 ns
c) 100 ns
d) none
Q. The resolution for a DAC is given by 0.4% then no. of bits of DAC is
a) 8- bits
b) 16- bits
c) 32- bits
d) none
Ans: 8- bits
41) The chip capacity is 256 bits, then the no.of chips required to build 1024 B memory Is
a) 32
b) 16
c) 15
d) 4
Q. Which of the following are correct?
1)A flip-flop is used to store 1-bit of information
2)Race around condition occurs in JK flip flop when both the inputs are 1
3)Master slave flip flop is used to store 2 bits of information
4)A transparent latch consists of a D- flip flop
a) 1,2,3
b) 1,3,4
c) 1,2,4
d) 2,3,4
Ans: 1,2,4
Q. output resistance of ideal OP AMP is
a) 0
b) 1
c) infinite
d) very high
ANS: 0
Q. CMRR of an OP AMP is given as 80db and Ad is 20000.Value of Acm will be
a) 4
b) 8
c) 2
d) 1
Ans: 2
Q.Si,Ge lie in ........block of periodic table
a) III
b) V
c) IV A
d) IV B
Ans: IV A
Q.to obtain 10 mV resolution on 5 V range how many bit DAC is to be used
a) 4
b) 8
c) 16
d) 32
Q.% resolution of a 10 bit ADC
a) 1.588%
b) 0.392%
c) 0.0978%
d) 0.0244%
Ans: 0.0978%
Q.Efficiency of half wave rectifier
a) 45%
b) 50%
c) 86%
d) 100%
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