2013
Question Booklet Code
A
EC : ELECTRONICS AND COMMUNICATION ENGINEERING
Duration: Three Hours
Maximum Marks: 100
Read the following instructions carefully.
1. Do not open the seal of the Question Booklet until you are asked to do so by the invigilator.
2. Take out the Optical Response Sheet (ORS) from this Question Booklet without breaking the seal
and read the instructions printed on the ORS carefully. If you find that either:
a. The Question Booklet Code printed at the right hand top corner of this page does not match with
the Question Booklet Code at the right hand top corner of the ORS or
b. The Question Paper Code preceding the Registration number on the ORS is not EC,
then exchange the booklet immediately with a new sealed Question Booklet.
3. On the right hand side of the ORS, using ONLY a black ink ballpoint pen, (i) darken the appropriate
bubble under each digit of your registration number and (ii) write your registration number, your
name and name of the examination centre and put your signature at the specified location.
4. This Question Booklet contains 24 pages including blank pages for rough work. After you are
permitted to open the seal, check all pages and report discrepancies, if any, to the invigilator.
5. There are a total of 65 questions carrying 100 marks. All these questions are of objective type. Each
question has only one correct answer. Questions must be answered on the left hand side of the ORS
by darkening the appropriate bubble (marked A, B, C, D) using ONLY a black ink ballpoint pen
against the question number. For each question darken the bubble of the correct answer. More
than one answer bubbled against a question will be treated as an incorrect response.
6. Since bubbles darkened by the black ink ballpoint pen cannot be erased, candidates should darken the
bubbles in the ORS very carefully.
7. Questions Q.1 - Q.25 carry 1 mark each. Questions Q.26 - Q.55 carry 2 marks each. The 2 marks
questions include two pairs of common data questions and two pairs of linked answer questions. The
answer to the second question of the linked answer questions depends on the answer to the first
question of the pair. If the first question in the linked pair is wrongly answered or is not attempted,
then the answer to the second question in the pair will not be evaluated.
8. Questions Q.56 - Q.65 belong to General Aptitude (GA) section and carry a total of 15 marks.
Questions Q.56 - Q.60 carry 1 mark each, and questions Q.61 - Q.65 carry 2 marks each.
9. Questions not attempted will result in zero mark and wrong answers will result in NEGATIVE
marks. For all 1 mark questions, ⅓ mark will be deducted for each wrong answer. For all 2 marks
questions, ⅔ mark will be deducted for each wrong answer. However, in the case of the linked
answer question pair, there will be negative marks only for wrong answer to the first question and no
negative marks for wrong answer to the second question.
10. Calculator is allowed whereas charts, graph sheets or tables are NOT allowed in the examination hall.
11. Rough work can be done on the Question Booklet itself. Blank pages are provided at the end of the
Question Booklet for rough work.
12. Before the start of the examination, write your name and registration number in the space provided
below using a black ink ballpoint pen.
Name
Registration Number
EC
EC-A
1/24
2013
ELECTRONICS & COMMN. ENGG. - EC
Q.1 to Q.25 carry one mark each.
Q.1
A bulb in a staircase has two switches, one switch being at the ground floor and the other one at the
first floor. The bulb can be turned ON and also can be turned OFF by any one of the switches
irrespective of the state of the other switch. The logic of switching of the bulb resembles
(A) an AND gate
(B) an OR gate
(C) an XOR gate
(D) a NAND gate
r
r r
Q.2
Consider a vector field A(r ). The closed loop line integral ∫A•dl
can be expressed as
r
r
(A)
(∇× A) • ds
over the closed surface bounded by the loop
∫∫
r
(B)
(∇ • A)dv
over the closed volume bounded by the loop
∫∫∫
r
(C)
(∇ • A)dv
over the open volume bounded by the loop
∫∫∫
r
r
(D)
(∇ × A) • ds
over the open surface bounded by the loop
∫∫
Q.3
Two systems with impulse responses
h
(t) and
h
(t) are connected in cascade. Then the overall
1
2
impulse response of the cascaded system is given by
(A) product of
h
(t) and
h
(t)
1
2
(B) sum of
h
(t) andh
(t)
1
2
(C) convolution of
h
(t) and
h
(t)
1
2
(D) subtraction of
h
(t) from
h
(t)
2
1
Q.4
In a forward biased pn junction diode, the sequence of events that best describes the mechanism of
current flow is
(A) injection, and subsequent diffusion and recombination of minority carriers
(B) injection, and subsequent drift and generation of minority carriers
(C) extraction, and subsequent diffusion and generation of minority carriers
(D) extraction, and subsequent drift and recombination of minority carriers
Q.5
In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or
water vapor) produces
(A) superior quality oxide with a higher growth rate
(B) inferior quality oxide with a higher growth rate
(C) inferior quality oxide with a lower growth rate
(D) superior quality oxide with a lower growth rate
Q.6
The maximum value of θ until which the approximation sinθ ≈ θ holds to within 10% error is
(A) 10°
(B) 18°
(C) 50°
(D) 90°
EC-A
2/24
2013
ELECTRONICS & COMMN. ENGG. - EC
r
Q.7
The divergence of the vector field
A = xa
+ ya
+ za
is
x
y
z
(A) 0
(B) 1/3
(C) 1
(D) 3
Q.8
The impulse response of a system is h(t) = t u(t) . For an input u(t −1) , the output is
2
t(t −1)
2
2
t
(t −1)
t
−1
(A)
u(t)
(B)
u(t−1)
(C)
u(t−1)
(D)
u(t−1)
2
2
2
2
The Bode plot of a transfer function G (s) is shown in the figure below.
Q.9
The gain (20 log
G(s)
) is 32 dB and −8 dB at 1 rad/s and 10 rad/s respectively. The phase is
negative for all ω. Then G (s) is
3
32
(A)
(B) 3
(C)
32
(D)
s
2
s
2
s
s
Q.10 In the circuit shown below what is the output voltage (Vout) if a silicon transistor Q and an ideal
op-amp are used?
+15 V
Q
1 kΩ
-
Vout
+
5V
- 15 V
(A)
15 V
(B)
0.7 V
(C)
0.7 V
(D)
15 V
EC-A
3/24
2013
ELECTRONICS & COMMN. ENGG. - EC
Q.11 Consider a delta connection of resistors and its equivalent star connection as shown below. If all
elements of the delta connection are scaled by a factor k, k> 0, the elements of the corresponding
star equivalent will be scaled by a factor of
Ra
RC
RB
Rb
Rc
RA
(A) k2
(B) k
(C) 1/k
(D)
k
Q.12 For 8085 microprocessor, the following program is executed.
MVI A, 05H;
MVI B, 05H;
PTR: ADD B;
DCR B;
JNZ PTR;
ADI 03H;
HLT;
At the end of program, accumulator contains
(A) 17H
(B) 20H
(C) 23H
(D) 05H
Q.13 The bit rate of a digital communication system is R kbits/s. The modulation used is 32-QAM. The
minimum bandwidth required for ISI free transmission is
(A) R/10 Hz
(B) R/10 kHz
(C) R/5 Hz
(D) R/5 kHz
Q.14 For a periodic signal v (t) = 30 sin100 t +10 cos 300 t + 6 sin (500 t + π / 4) , the fundamental frequency in
rad/s is
(A) 100
(B) 300
(C) 500
(D) 1500
EC-A
4/24
2013
ELECTRONICS & COMMN. ENGG. - EC
Q.15 In a voltage-voltage feedback as shown below, which one of the following statements is TRUE if
the gain k is increased?
(A) The input impedance increases and output impedance decreases.
(B) The input impedance increases and output impedance also increases.
(C) The input impedance decreases and output impedance also decreases.
(D) The input impedance decreases and output impedance increases.
Q.16
A band-limited signal with a maximum frequency of 5 kHz is to be sampled. According to the
sampling theorem, the sampling frequency which is not valid is
(A) 5 kHz
(B) 12 kHz
(C) 15 kHz
(D) 20 kHz
Q.17
In a MOSFET operating in the saturation region, the channel length modulation effect causes
(A) an increase in the gate-source capacitance
(B) a decrease in the transconductance
(C) a decrease in the unity-gain cutoff frequency
(D) a decrease in the output resistance
Q.18
Which one of the following statements is NOT TRUE for a continuous time causal and stable
LTI system?
(A) All the poles of the system must lie on the left side of the jω axis.
(B) Zeros of the system can lie anywhere in the s-plane.
(C) All the poles must lie within
s
=1.
(D) All the roots of the characteristic equation must be located on the left side of the
jω axis.
Q.19
The minimum eigenvalue of the following matrix is
3
5
2
5
12
7
2
7
5
(A) 0
(B) 1
(C) 2
(D) 3
EC-A
5/24
MCA Final year 6th Sem
