BARC previous questions sample paper for electronics(ECE)-2016

SOME GOOD PREVIOUS QUESTIONS TO PRACTICE

 

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) ? 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 ? 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>> ? L, G >> ? C)
(D) very high frequency range (R<< ? L, G << ? 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 ? of the transistor
c) Both Temperature & ?
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 ? 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, , ? the voltage across C at time ? = 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