electronics sample paper 1

7/25/2019 Electronics Sample Paper 1

1/13

Q.l Q 25 carry one mark each

Q.1

f

A=

0

in

logic

expre

ssion

Z =[A

EF

BC D] [A+

DE

BC DEL then

(A) Z = 0 (B) Z =

(C)

Z= BC (D)

Z=

BC

Q 2

A

card

is

drawn at random

from

an

ordinary

deck

of 52 playing cards.

f

we

are told

that

card is heart

1

then information is

(A)

2.12 bi ts (B) 2

bits

(C)

3.46

bi t

s (

D)

31.36

bi t

s

Q 3

A

DS/BPSK

spread

spectrum signal

has

a processing

gain of

500. f the desired

error

probability

is 10

5

and

cb/

J

0

) required to obtain an error probabilit

y

of

10

5

for

binary

PSK

is 9.5

dB

1

then the

Jamming

margin against

a

containers tone

jammer is

(

A

23.6 dB (B) 17.5 dB

(C)

117.4 dB

D)

109.0 dB

Q 4

A

60

n

coaxial cable feeds a

75

+

j25

n

dipole

antenna.

The

voltage reflection

coefficient

r and standing

wave

ratio s are

respectively

A

) 0.212 L48.55 o 1.538 (B) 0.486 68.4o 2.628

(C) 0.486 L41.45 o 2.682

D

) 0.212L68.4

1

1.538

Q 5

The

directive gain

of an

antenna is 36 dB. t the antenna radiates 15 kW

at

a

distance

of

60

km

1

the

time

average power

density

at that

distance

is

A

) 9.42 f W / m

2

(B) 6.83 m W/ m

2

C

) 1.32

mW

m

2

D

) 10.46

mW

m

2

Q 6 f

A is a

3-

rowed

square matrix such that I

A

I

2

1

then I

dj (

adj

A

2

) I

is

equal to

(A) 2

4

(B) 2

8

(D)

None

of

these

Q.7

[

2

log

tan x x

is

equal to

C

) ;

log,2

(D)

None

of

these

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2/13

Q.8 An

anti-aircraft

gun

can take a

maximum of

4

shots

at

an enemy

plane moving away

from it. The probabilities

of hitting

the plane at

the

first, second, third

and fourth shot

are

0.4, 0.3, 0.2

and

0.1 respectively.

The

probability

that

the

gun hits

the plane is

A) 0.76 B) 0.4096

C) 0.6976

D)

None

of these

Q.9 The

following fields exist in charge free regions

Q.10

P =

60sin wt +lOx)

z Q = lO cos wt-

2p)

p

The

possible

electromagnetic

fields are

A) P Q

C) P R

S = ls inBsin wt-

6r ue

r

B) R S

D)

Q S

A random process

has the

power

density

spectrum

Pxx w =

6

u u

3

. The

average

power

in

process is

[

+ )

A) 1/4

C) 5/8

B) 3/8

D)

1/2

Q.11 The Bode

plot shown below

represent

d

100 dB

~ ~ w

A 100s

2

)

1

+ O.ls)

3

100s

2

C)

1

+ O.ls)

5

w 10

B)

1000s

2

1

+ O.ls)

3

D)

lOOOi

1 + O.ls)

5

Q.12 he

forward

transfer

function

of

a

ufb system

is

s =

8

~

2

) .

The system

1s stable

for

A) K < 1

C)

K

2

B) K > 1

D)

K

2

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3/13

Q 13 Consider

the ufb system shown

below

R s ) - , ~ 1

lt------ -J

s)

The root-loci,

as o.

is varied, will be

j.JJ

A)

-1

B)

C)

1

D)

Q 14

The Fourier series coefficient for the periodic signal shown

belo

w is

x t)

I I

I I I I

TI

4TI

~ ~ ~ ~ ~ ~ ~ ~ t

0

TI

4TI

3 3

A)

2 ~ k e

: \ 4 k - 1

(

.4d) )

(C) e

1

- 3

1

2nk

Q 15 Th

e

z transform

of

3n

u

1]

is

A)

3: z l I>

3

C) 3 ~

z l z I>

3

B) j 2 ~ k e

:\

k

)-1

D)

2 n 1 e - 1

B) 3 :

z I I

electronics sample paper 1

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