**BARC Bhabha Atomic Research Center previous years question papers of electronics and electrical BARC Aptitude question papers, BARC placement papers questions**

**BARC Bhabha Atomic Research Center Electronics and electrical technical questions of BARC placement papers **

1 Consider a transmission line of characteristic impedance 50 ohms and the line is terminated at one end by +j50 ohms, the VSWR produced in the transmission line will be

(A) +1

(B)zero

(C)infinity

(D)-1

2 In a certain medium E = 10 Cos(108t–3y) a xV/m. What type of medium is it?

(A) Free space

(B)Lossy dielectric

(C)Lossless dielectric

(D)Perfect conductor

3 If D⋅∇=∈∇.Eand∇.J = σ∇.Ein a given material, the material is said to be

(A) Linear

(B)Homogeneous

(C) Isotropic

(D) Linear & Homogeneous

4 For a 300 Ω antenna operating with 5A of current, the radiated power is

(A) 7500 W

(B) 750 W

(C)75 W

(D)7500 mW

5. An OPAMP has a slew rate of 5 V/μ S .The largest sine wave O/P voltage possible at a frequency of 1MHZ is

(a) 10 volts

(b) 15 volts

(c) 5/3 vo lts

(d)5/2 volts

6 The early effect in a bipolar junction transistor is caused by

(a) fast turn-on

(b)fast turn-off

(c) large collector-base reverse bias

(d) large emitter-base forward bias

7 MOSFET can be used as a

(a) current controlled capacitor

(b) voltage controlled capacitor

(c) current controlled inductor

(d) voltage controlled inductors

8 An AM signal is detected using an envelop detector. The carrier frequency and modulating signal frequency are 1MHz and 2 kHz respectively. An appropriate value for the time constant of the envelope

detector is.

(A) 500 μsec

(B) 20 μsec

(C) 0.2 μsec

(D) 1μ sec

9 An AM modulator has output x(t)=A cos400 πt+Bcos 380 πt +Bcos420πt and The carrier power is 100 W and the efficiency is 40%. The value of A and B are

(A) 14.14, 8.16

(B) 50, 10

(C) 22.36, 13.46

(D) None of the above

10 A super heterodyne receiver is designed to receive transmitted signals between 5 and 10 MHz. High-side tuning is to be used. The tuning range of the local oscillator for IF frequency 500 kHz would be

(A) 4.5 MHz-9.5 MHz

(B) 5.5 MHz-10.5 MHz

(C) 4.5 MHz-10.5 MHz

(D) none of these

11 An analog signal is sampled at 36 kHz and quantized into 256 levels.The time duration of a bit of the binary coded signal is

(A) 5.78μs

(B) 3.47μs

(C) 6.43 ms

(D) 7.86 ms

12 The minimum sampling frequency (in samples/sec) required to reconstruct the following signal form its samples without distortion would be x(t)= 5(sin2 π 1000t/πt)3 +7(sin 2πt 1000t/πt)2

(A)2×103

(B)4×103

(C) 6×103

(D) 8×103

13 Three identical amplifier, each having a spot effective input noise temperature of 125 K and available power G are cascaded. The overall spot effective input noise temperature of the cascade is 155 K. The Gis

(A) 3

(B) 5

(C) 7

(D) 9

14 In the Op-Amp circuit shown, assume that the diode current follows the equation I=I _{ s} exp(V/Vt) Vi=_{2}V , V_{o}=V_{01}and for V_{i}=4V , V_{o}=V_{02}The relationship between V_{01}andV_{02}is

15 The counter shown in fig. below is a

(A) MOD–8 up counter

(B) MOD–8 down counter

(C) MOD–6 up counter

(D) MOD–6 down counter

16 The MUX shown in fig. multiplexer. The output Z is