BARC Electronics-Communication-Engineering-ECE

BARC-Bhabha Atomic Research Center Previous years Electronics and electrical question papers.  BARC OCES DGFS examination procedure,test pattern,selection procedure.  BARC previous years solved question papers of different exams 

BARC Electronics and electrical Question papers

1 Differential amplifiers are used in
a. instrumentation amplifiers
b. voltage followers
c. voltage regulators
d. buffers

2 The output voltage Vo of the above circuit is 

a.-6V
b.-5V
c.-1.2V
d.-0.2V

3 The ideal OP-AMP has the following characteristics.
a) Ri=∞ ,A=∞ ,R0=0
b) Ri=0 ,A=∞ ,R0=0
c) Ri=∞ ,A=∞ ,R0=∞
d) Ri=0 ,A=∞ ,R0=∞

4 How many op-amps are required to implement this equation 

A. 2
B. 3
C. 4
D. 1


5 A very brief, high voltage spike on an ac power line is called as
A. A bleeder
B. An arc
C. A transient
D. An avalanche
E. A clipped peak

6 You can find the zener diode in
A. The mixer in a superheterodyne receiver
B. The PLL in a circuit for detecting FM
C. The product detector in a receiver for SSB
D. The voltage regulator in a power supply
E. The AF oscillator in an AFSK transmitter

7 A network function can be completely specified by:
(A) Real parts of zeros
(B)Poles and zeros
(C)Real parts of poles
(D)Poles, zeros and a scale factor

8 A unit impulse voltage is applied to one port network having two linear components. If the current through the network is 0 for t<0 and decaysexponentially for t>0then the network consists of
(A) R and L in series
(B)R and L in parallel
(C)R and C in parallel
(D)R and C in series

9 The Q-factor of a parallel resonance circuit consisting of an inductance of value 1mH, capacitance of value 10-5 F and a resistance of 100 ohms is
(A) 1
(B)10
(C) π 20
(D) 100

10 In a travelling electromagnetic wave, E and H vector fields are
(A) perpendicular in space .
(B) parallel in space.
(C) E is in the direction of wave travel.
(D) H is in the direction of wave travel. 

11 The lower cut -off frequency of a rectangular wave guide with inside dimensions (3 × 4.5 cm) operating at 10 GHz is
(A) 10 GHz.
(B)9 GHz.
(C) 10/9GHz.
(D) 10/3GHz

12 The intrinsic impedance of free space is
(A) 75 ohm.
(B)73 ohm.
(C)120 π ohm.
(D)377ohm

13 Which one of the following conditions will not guarantee a distortion less transmission line
(A)R = 0 = G
(B)RC = LG
(C) very low frequency range (R>> ω L, G >> ω C)
(D) very high frequency range (R<< ω L, G << ω C)

14 MOSFET can be used as a
(a) current controlled capacitor 
(b) voltage controlled capacitor
(c) current controlled inductor 
(d) voltage controlled inductors

15 In a common emitter, unbypassed resister provides
(a)voltage shunt feedback 
(b)current series feedback
(c)negative voltage feedback 
(d)positive current feedback

16 Introducing a resistor in the emitter of a common amplifier stabilizes the dc operating point against variations in
a) Only the temperature 
b) only the β of the transistor
c) Both Temperature & β 
d) None of the above

17 For the circuit shown in Fig.4, the voltage across the last resistor is V.All resistors are of Ω 1 .The Vs is given by 

(A) 13V. 
(B) 8V.
(C) 4V. 
(D)1V

18 The network has a network function Z(s)=s(s+2)/(s+3)(s+4)
(A)not a positive real function. 
(B)RL network.
(C) RC network. 
(D)LC network

19 For a series R-C circuit excited by a d-c voltageof 10V, and with time-constant s, , τ the voltage across C at time τ = t is given by
A.10(1-e-1) v 
B.10(2-e-2) v
C.10-e-1volts
D.1-e-1

20 A 2 port network using Z parameter representation is said to bereciprocal if
A.Z11=Z22
B.Z12=Z21
C.Z12=-Z21
D.Z11–2Z22=0